vvEPA
United States
Environmental Protection
Agency
Prevention, Pesticides and
Toxic Substances
Occupational Safety and Health Administration
EPA-750-b-92-001
May 1993
A Guide To Heat Stress
In Agriculture
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There are other materials about the Worker Protection Standard developed by EPA, including a safety, poster,.
handbooks on pesticide safety for pesticide handlers and for agricultural workers, and a manual for agricultural
employers. For more information about safety training and about the revised Worker Protection Standard,
contact:
Occupational Safety Branch (7506C)
Office of Pesticide Pi-ograms
U.S. Environmental Protection Agency
401 M Street, S. W.
Washington, D.C. 20460
(703) 305-7666
For More Information
If you need more information about the Worker Protection Standard or have questions or concerns about
pesticides, contact the agency responsible for regulating pesticides in your area or the EPA Regional Office
nearest you.
Region 1 (MA, CT, Rl, NH, VT, ME)
U.S. Environmental Protection Agency, Region 1
Pesticides and Toxic Substances Branch (APT)
1 Congress St.
Boston, MA 02203
(617)565-3273
Region 2 (NY, NJ, PR, VI)
U.S. Environmental Protection Agency, Region 2
Pesticides and Toxic Substances Branch (MS-105)
2890 Woodbridge Ave., Building #10
Edison, NJ 08837-3679
(908)321-6765
Region 3 (PA, MD, VA, WV, DE)
U.S. Environmental Protection Agency, Region 3
Toxics and Pesticides Branch (3AT-30)
841 Chestnut Building
Philadelphia, PA 19107
(215)597-8598
Region 4 (GA, NC, SC, AL, MS, KY, FL, TN)
U.S. Environmental Protection Agency, Region 4
Pesticides & Toxic Substances Branch
(4-APT-MD)
345 Courtland St., N.E.
Atlanta, GA 30365
(404)347-5201
Region 5 (IL, Ml, MN, IN, OH, Wl)
U.S. Environmental Protection Agency, Region 5
Pesticides and Toxic Substances Branch (SP-14-J)
77 W. Jackson Blvd.
Chicago, IL 60604
(312)886-6006
Region 6 (TX, OK, AR, LA, NM)
U.S. Environmental Protection Agency, Region 6
Pesticides and Toxics Branch (6T-P)
1445 Ross Ave.
Dallas, TX 75202-2733
(214) 655-7235
Region 7 (MO, KS, I A, NE)
U.S. Environmental Protection Agency, Region 7
Toxics and Pesticides Branch (TOPE)
726 Minnesota Ave.
Kansas City, KS 66101
(913)551-7020
Region 8 (CO, MT, ND, SD, UT, WY)
U.S. Environmental Protection Agency, Region 8
Toxic Substances Branch (8ART-TS)
One Denver Place, Suite 500
999 18th St.
Denver, CO 80202-2405
(303) 293-1730
Region9 (CA, NV, AZ, HI, GU)
U.S. Environmental Protection Agency, Region 9
Pesticides and Toxics Branch (A-4)
75 Hawthorne St.
San Francisco, CA 94105
(415) 744-1090
Region 10 (WA, OR, ID, AK)
U.S. Environmental Protection Agency, Region 10
Pesticides and Toxic Substances Branch (AT-083)
1200 Sixth Ave.
Seattle, WA 98191
(206) 553-1918
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United States
Environmental Protection
Agency
Occupational
Safety and Health
Administration
&EPA
A Guide
To Heat Stress
In Agriculture
Recycled/Recyclable
Printed with Soy/Canola Ink on paper that
contains a\ least SCOfe recycled Tiber
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For more information about the Occupational Safety and Health Act, contact the OSHA Regional Office
nearest you:
Region 1 (CT,*, MA, ME, NH, RI, VT*)
OSHA, Region 1
133 Portland Street, 1st Floor
Boston, MA 02114
(617) 565-7164
Region 2 (NJ, NY,*, PR,* VI*)
OSHA, Region 2
201 Varick Street, Room 670
New York, NY 10014
(212) 377-2378
Region 3 (DC, DE, MD,* PA, VA,* WV)
OSHA, Region 3
Gateway Building, Suite 2100
3535 Market Street
Philadelphia, PA 19104
(215) 596-1201
Region 4 (AL, FL, GA, KY,* MS, NC,* SC,* TN*)
OSHA, Region 4
1375 Peachtree, Street, N.E., Suite 587
Atlanta, GA 30367
(404) 347-3573
Region 5 (EL, IN,* MI,* MN,* OH, Wl)
OSHA, Region 5
230 South Dearborn Street, Room 3244
Chicago, IL 60604
(312) 353-2220
Region 6 (AR, LA, NM,* OK, TX)
OSHA, Region 6
525 Griffin Street, Room 602
Dallas, TX 75202
(214) 767-4731
Region 7 (LA,,* KS, MO, NE)
OSHA, Region 7
911 Walnut Street, Room 406
Kansas City, MO 64106
(816) 426-5861
Region 8 (CO, MT, ND, SD, UT,* WY*)
OSHA, Region 8
Federal Building, Room 1576
1961 Stout Street
Denver, CO 80294
(303) 844-3061
Region 9 (AZ,* CA,* GU, HI,* NV*)
OSHA, Region 9
71 Stevenson Street, 4th Floor
San Francisco, CA 94105
(415) 744-6670
Region 10 (AK,* ID, OR,* WA*)
OSHA, Region 10
1111 Third Avenue, Suite 715
Seattle, WA 98101-3212
(206) 553-5930
*These states and territories operate their own OSHA-approved job safety and health programs (Connecticut
and New York plans cover public employees only). States with approved programs must have a standard that
is identical to, or at least as effective, as the Federal standard.
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PREFACE
This guide was written to help private and commercial pesti-
cide applicators and agricultural employers protect their
workers from heat illness. It applies recognized heat stress man-
agement principles to the particular conditions of agriculture.
Special emphasis has been given to the problems of control-
ling heat stress among pesticide handlers and "early entry"
workers (workers who go into an area while entry is restricted
after treatment with pesticides) who must wear protective gear.
EPA's revised Worker Protection Standard requires that these
workers be instructed in the prevention, recognition, and first-
aid treatment of heat illness and that they not be allowed or
directed to perform handling or early entry activities unless
appropriate measures are taken, if necessary, to prevent heat
illness.
The basic program presented here is intended to be "best
practice." Some items will not be practical in every particular
situation and agricultural establishments will need to adapt this
program .to their specific conditions of work.
Eight principal sources were used in developing this guide.
These are listed as references 1 to 8 in the back. Additional refer-
ences are cited throughout the text and also listed in the back.
Note: The revised Worker Protection Standard uses the term "personal protective
equipment" or "PPE" to designate devices and garments worn to protect the body
against contact with pesticides or pesticide residues. The revised standard distin-
guishes between certain items of work clothing, such as long-sleeved shirts and long
pants, which had been included under the definition of "protective clothing" in an
earlier standard, and more protective garments. However, the term "protective
clothing" is also in general use in occupational safety and health to designate any
article offering skin and/or body protection. To avoid confusion, the term "protective
clothing" is not used here.
DISCLAIMER
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use by the U.S. Environmental Protection Agency or the Occupa-
tional Safety and Health Administration.
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CONTENTS
INTRODUCTION • -
What Is Heat Stress? •• • 1
The Need for a Heat Stress Program in Agriculture 1
Heat Illnesses and First Aid Measures 4
CONTROLLING HEAT STRESS MADE SIMPLE 5
Key Elements
Basic Steps • 5
Heat Illness and Pesticide Poisoning 7
A BASIC PROGRAM TO CONTROL HEAT STRESS 8
STEP 1: Assign Responsibility for Heat Stress Problems 9
STEP 2: Train Workers and Supervisors • 10
STEP 3: Acclimatize Workers • • n
STEP 4: For Each Task, Take into Account
the Conditions of Work and of the Workers 13
Evaluating Work Assignments 13
Evaluating the Risk of Heat Illness 15
STEP 5: Manage Work Activities 16
Setting Up Rest Breaks 16
Rotating Tasks 20
Shifting Times for Certain Activities 21
Postponing Non-Essential Tasks During Heat Spells 21
Children 21
STEP 6: Establish A Drinking Water Program 22
Dehydration 22
Drinking Water and Fluid Replacement 23
Soft Drinks 24
Alcohol 24
Salt and Other Electrolytes • 25
ii
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STEP 7: Take Additional Measures ....26
Problems from Protective Garments 26
Special Cooling Garments .. 26
Cooling Vests and Chemical-Resistant Suits i 26
Selecting Cooling Vests L 27
Maintaining Cooling Vests : 27
Other Cooling Garments 27
Select Lighter Weight Protective Gear and Cooler Respirators 27
Shade 28
Air-Conditioned Cabs on Mobile Equipment 1 28
Modifying Pesticide Usage and Handling 1 28
Protecting Pilots 28
STEP 8: Give First Aid When Workers Become HI I ..32
Setting Up A First Aid Program ,... i 32
Recognition of Heat Illness '. 32
General Principles ; i 32
Treating Heat Stroke ; 33
Fainting and Salt Depletion Heat Exhaustion ! 33
Following Up on Incidents ' 33
REFERENCES.
.34
APPENDICES i 37
Appendix I Suppliers of Cooling Garments and Selected Devices
for Evaluating Heat Stress and Heat Stress Conditions J 37
Appendix II Sources for Obtaining Local Climate Profiles i 38
Appendix III Methods for Deriving Tables 6 and 7 ' 41
Appendix IV Background on the Fighter Index of Thermal Stress 44
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ACKNOWLEDGEMENTS
This guide was prepared by the Occupational
Safety Branch in the Field Operations Division of
EPA's Office of Pesticide Programs in conjunction
with OSHA. Steve Shapiro was the principal author.
EPA and OSHA are issuing this guide jointly.
Many people generously provided comments,
valuable information, and other assistance, greatly
improving its contents. EPA and OSHA are respon-
sible for the guide's contents; but to the extent this
guide is helpful to people in controlling heat stress,
much of the credit must go to the following persons:
Patricia P. Breslin, Alan P. Nielsen, Michael Royer,
and Sally A. McDonald, EPA
Elizabeth Collins, Eastern Research Group
Austin Henschel, Roger Jensen, NIOSH
Sarah A. Nunnelly, U.S. Air Force
Ching-Tsen Bien, Joe Nycz, Bill Albano, Harry D.
Allendorf, OSHA
Sheldon A. Wagner, Oregon State University
Harold Collins, National Agricultural Aviation Asso-
ciation
Stuart A. Turner, Turner and Company
Robert McCarty and staff, Mississippi Department of
Agriculture and Commerce
Michael S. Uhart, National Oceanic and Atmospheric
Administration
Sharon M. Hughes, National Council of Agricultural
Employers
Edwin W. Minch, Arizona Department of Agricul-
ture
Bobby F. McKown, Florida Citrus Mutual
Chin Lee, University of Central Florida
Thomas E. Bernard, University of South Florida
William T. Matthew, Kenneth Kraning, U.S. Army
Research Institute of Environmental Medicine
Jerry D. Ramsey, Texas Tech University
Ralph F. Goldman, Multi-Tech Corporation
Lawrence Armstrong, University of Connecticut
Steven B. Auerbach, Centers for Disease Control
Fred Halvorsen, OHM Corporation
Barbara A. Avellini, Nancy A. Pimental, Navy
Clothing and Textile Research Facility
Guy Banta, U.S. Coast Guard
Mark Lyons, Farmworker Support Committee
E. Roberta Ryder, National Migrant Resource Pro-
gram
Dennis B. Gibbons, California EPA
Carol Conroy, California Occupational Health Pro-
gram
Most photographs by Earl Dotter (photo on page 26
courtesy of Steele Inc.). Editing, design and typeset-
ting prepared under Contract #OW-1867-NALX.
iv
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REVIEWERS OF HEAT STRESS GUIDE — U.S. GOVERNMENT
Austin Henschel, Ph.D.
Richard W. Niemeier, Ph.D.,
Director
Jerome P. Flesch
G. Kent Hatfield
NIOSH DSDTT
Cincinnati, Ohio
Nina L. Turner. Ph.D.
NIOSH DSR
Morgantown, West Virginia
Ching-Tsen Bien
OSHA Tech Support
Washington, D.C.
Bonnie Poli
USDA Extension Service
Washington, D.C.
Larry Gross
USDA Forest Service
Washington, D.C.
Lawrence E. Armstrong, Ph.D.
William T. Matthew
Kenneth Kraning, Ph.D.
Heat Stress Research Division
U.S. Army Research Institute
of Environmental Medicine
Natick, Massachusetts
Sarah A. Nunnelly, M.D.
U.S. Air Force
School of Aerospace Medicine
Brooks Air Force Base, Texas
William E. Collins, Ph.D.,
Director
Civil Aeromedical Institute
FAA Aeronautical Center
Oklahoma City, Oklahoma
Robert V. Bielarski
Patricia P. Breslin, Ph.D.
Sally A. McDonald
Judy A. Smith
Office of Pesticide Programs,
EPA
Washington, D.C. i
Rodney D. Turpin ,
OSWER Environmental
Response Branch, EPA
Edison, New Jersey '
Fred Stockmeier
EPA Region V
Chicago, Illinois
Arthur D. Schwope
(Contractor to EPA's Office of
Research and Development)
A. D. Little
Cambridge, Massachusetts
Ralph F. Goldman, Ph.D.
(Consultant to EPA's Office of
Research and Development)
Multi-Tech Corporation
Framingham, Massachusetts
REVIEWERS OF HEAT STRESS GUIDE — OUTSIDE U.S. GOVERNMENT
Sharon M. Hughes
Executive Vice President
National Council of
Agricultural Employers
Washington, D.C.
Robert D. DeBruyn, President
DeBruyn Produce Co.
Zeeland, Michigan
W.D. Balfour, Jr., President
Oahu Sugar Company
Waipahu, Hawaii
Ned Meister
Director Regulatory Affairs
Texas Farm Bureau
Waco, Texas
Bobby F. McKown
Executive Vice President
Florida Citrus Mutual
Lakeland, Florida
Charles Matthews
Florida Fruit & Vegetable
Association
Orlando, Florida
Harold Collins
National Agricultural Aviation
Association
Washington, D.C.
Stuart A. Turner
Turner and Company
Kennywick, Washington
Dennis B. Gibbons, CIH
California EPA
Worker Health and Safety
Branch
Sacramento, California
Robert McCarty, Deputy
Director
Division of Plant Industry
Mississippi Dept. of
Agriculture and Commerce
Mississippi State, Mississippi
Von H. McCaskill, Ph.D.
Department of Fertilizer and
Pesticide Control
S.C. Dept. of Agriculture
Clemson, South Carolina
Edwin W. Minch, Ph.D.
Arizona Dept. of Agriculture
Phoenix, Arizona
Mark Lyons
Farmworker Support
Committee •
Glassboro, New Jersejr
I
i
Juan Duran, Chairmari
Campesinos, Migrantes,
Trabaj adores de Agriculture
Crystal City, Texas
Anne Katten, M.P.H.
Ralph Lightstone i
California Rural Legal
Assistance Foundation
Sacramento, California
Marion Moses, M.D. i
Farmworkers Pesticide Project
San Francisco, California
John Moran
Laborers' National Health and
Safety Fund
Washington, D.C.
J. Davitt McAteer
Occupational Safety and
Health Law Center
Shepherdstown, West Virginia
George W. Ware, Ph.D.
Arizona Agricultural
Experiment Station
College of Agriculture
University of Arizona
Tucson, Arizona
Elihu D. Richter, M.D.,
Head, Unit of Occupational and
Environmental Medicine
Hebrew University Medical
School
Jerusalem, Israel
Thomas E. Bernard, Ph.D.
College of Public Health
University of South Florida
Tampa, Florida
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INTRODUCTION
When the body becomes
overheated, workers get
weaker, become tired
sooner, and may be less
alert, less able to use
good judgment, and less
able to do their jobs well.
WHAT IS HEAT STRESS?
Heat stress is the buildup
in the body of heat generated
by the muscles during work
and of heat coming from
warm and hot environments.
Heat exhaustion and heat
stroke result when the body is
subjected to more heat than it
can cope with.
Table 1 on page 4 lists the most
common forms of heat illness and
first aid measures for treating them.
When the body becomes over-
heated, less blood goes to the active
muscles, the brain, and other inter-
nal organs. Workers get weaker,
become tired sooner, and may be
less alert, less able to use good
judgment, and less able to do their
jobs well.
As strain from heat becomes more
severe, there can be a rapid rise in
body temperature and heart rate.
Workers may not realize that this is
happening because there is no pain.
Mental performance can be affected
with an increase in body tempera-
ture of 2°F above normal. An
increase of 5°F can result in serious
illness or death. The most serious
illness is heat stroke. Its effects can
include confusion, irrational behav-
ior, convulsions, coma, and even
death. Heat stroke can make survi-
vors very sensitive to heat for
months and cause varying degrees
of brain and kidney damage.12-36'49
More than 20 percent of people
afflicted by heat stroke die, even
[young and healthy adults. An aver-
age of nearly 500 people are killed
!each year in the United States by
the effects of heat. During the heat
'wave of 1980, over 1700 people died
from heat-related illness.38'57
Exposure to heat can have other
effects as well. Elevated temper-
atures in the scrotum for a short
period of time can cause men to
become relatively infertile for two to
three months. The effect of heat on
pregnancy is unclear, but it has been
recommended that high increases in
body temperature be especially
avoided during early pregnancy.
Children are more susceptible to
heat strain than adults. 27'28-41'44'67'74
During hot weather, heat illness
may be an underlying cause of other
; types of injuries, such as heart
attacks on the job, falls, and equip-
ment accidents arising from poor
judgment.
THE NEED FOR A HEAT
STRESS CONTROL PROGRAM
IN AGRICULTURE
In some regions, there are times
during the growing season when the
temperature stays above 90°F, even
;at night. High air temperatures and
'humidities put agricultural workers
iat special risk of heat illness.
Workers Compensation claims for
heat illness among agricultural
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REPORTS OF AGRICULTURAL WORKERS WHO BECAME ILL
WHILE WORKING IN THE HEAT
D
ecedent was identified as
., reportedly
34 years old. He was pronounced Dead On
Arrival at 19:22, on 5-26.
He worked for two days for the firm of
o
n September 3,.
.became ill while mixing,
At about 16:00, he became disoriented while v/orking
in the fields. Apparently the paramedics and an ambu-
lance were called at about 17:15. When he arrived at
______ Medical Center, his temperature was over 107
degrees. This was after spending the prior hour riding
in an air conditioned ambulance.
—K.S., Deputy Coroner
R
eceived a call reporting that
, female adult, 18,
had been pronounced dead in the
Medical Intensive Care Unit by
Dr. French at 13:59, May 30.
The decedent had been taken to
Hospital by her father at
14:30, May 28, after collapsing
while working in a cotton field.
The exact location could not be
determined. Upon arrival at the
hospital, the decedent had a rectal
temperature of 107.5 degrees
Fahrenheit. She was given oxygen
and packed in ice and by 15:10 her
temperature had dropped to 103.5.
She was suffering from seizures
and a constant flow of yellow,
watery diarrhea. She was unre-
sponsive the entire time she was at the hospital and
her pupils were three to four millimeters wide.
She was transferred to the Medical Intensive Care
Unit, where efforts were made to regulate her body
temperature and it was reduced to 100.4 degrees
Fahrenheit. The seizures continued, however, and she
began to have myocardial and renal (heart and kidney)
failure and disseminated intravascular coagulation
(blood clots throughout her body). She was on dialysis
when she died.
The decedent's family reported that she had been
working in the fields for three days prior to her col-
lapse. She had taken a tylenol for a headache around
noon, May 28, but immediately threw it up.
The United States Weather Bureau reported that the
high temperatures for May 25 through May 28 were 93,
96,102, and 107 degrees Fahrenheit, respectively.
—P. H., Deputy Coroner
loading, and applying pesticides to a strawberry
field. This person has worked for _ Farms for 3+
years. He has been spraying for only one year.
He said he felt fine when starting work at 7:30 a.m.
While applying, he wore rubber boots, rubber gloves,
torn rubber pants, a rubber jacket, goggles, and a dust
mask. He was working with malathion, benomyl, sul-
fur, and an adjuvant. He took off his rubber jacket at
noon due to the heat. Around 4 p.m., he developed
symptoms of dizziness, nausea, vomiting, and
lethargy. The grower told him to
buy a bottle of olive oil and drink it
as a remedy. He went home and
drank most of a bottle.
Later that night, he was taken to
_____ Community Hospital. He
was admitted and given a shower.
A blood sample was drawn to
determine cholinesterase activity.
The results showed that plasma
cholinesterase was 28% of low
laboratory normal and red blood
cell cholinesterase was 32% of low
laboratory normal. He was treated
with atropine and released from
the hospital five days later. He
returned to work without missing
any additional days from work.
When asked why this worker
was wearing a dust mask as
opposed to a respirator approved for use with organic
vapors, his employer said that respirators for organic
vapors were available, but the workers would take
them off whenever it got hot.
—Pesticide Enforcement Branch
he deceased came to.
. on June 20 and in-
JL quired if he could be hired, as he needed the work
and had experience. He began work the following day.
On June 27, while engaged in hoeing weeds, he col-
lapsed about 4 p.m. and was driven to
Hospital via pickup truck. On June 29 he was trans-
ferred to Hospital, where he died on July 9.
Autopsy indicated the deceased, 55, died as a result
of hyperthermia (heat stroke) with a significant con-
tributing factor of chronic ethylism (poisoning by
—Harry D, Allendorf, Area Director
9,35,45,60,72
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workers are among the highest of
any occupation.37-55
Pesticide handlers and early entry
workers are at even greater risk. The
special clothing and equipment they
wear for protection from exposure to
pesticides can restrict the evapora-
tion of sweat, blocking the body's
natural way of cooling itself, which
results in a buildup of body temper-
ature. Exposure to certain pesticides
can also produce sweating and there
can be combined effects with expo-
sure to heat. In addition, pesticides
are absorbed through hot, sweaty
skin more quickly than through cool
skin.
A program to prevent heat illness
will:
• Protect health. Heat illness is
preventable. When less severe forms
occur, they can be treated before
they become life-treatening.
• Improve safety. Workers with
mild effects of heat illness are more
likely to have accidents and use
poor judgment.
• Increase productivity. People
work slower and less efficiently
when they are under too much
strain from heat.
This guide presents steps employ-
ers can take to control heat stress
and protect workers from heat
illness. The methods include some
practices you may already follow,
whether or not you recognize them
as part of a heat stress control
program.
A summary of key points to fol-
low begins on page 5. A more
detailed program can be found on
pages 8 through 33. Supplementary
information can be found in the
appendices at the back of this guide.
Employers should begin with the
basic program starting on page 8
and adapt it to their particular needs
and circumstances.*
Employers, supervisors, and
workers each have an essential role
to play in preventing heat illness.
What is essential with employers is
their commitment to their heat
stress control program. What is
essential with supervisors and
employees is their following these
procedures, gaining experience, and
developing good judgment using
the principles in this guide.
Agricultural workers are at
special risk of heat illness.
Pesticide handlers and
early entry workers are at
even greater risk.
* Employers wishing to develop a more
detailed program than presented here should
consult references 1 through 8 at the back of
the Guide.
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Table 1
HEAT ILLNESSES AND FIRST AID MEASURES
illnast
Signs and Symptoms
Cause and Problem
Treatment*
Early heat Mild dizziness, fatigue, or irritability;
illness decreased concentration; impaired
judgment
Reduced flow of blood to the brain
May lead to heat exhaustion or heat
stroke
Loosen or remove clothing
Rest in shade 30 minutes or more
Drink water
Heat rash Tiny, blister-like red spots on the
("prickly neat") skin; pricking sensations
Commonly found on clothed areas
of the body
Sweat glands become plugged and
inflamed from unrelieved exposure
of skin to heat, humidity, and sweat
Clean skin, apply mild drying lotion
or cornstarch
Wear loose clothing
Preventable by regular bathing and
drying the skin and by periodic relief
from humid conditions of work
See physician if rash persists
Heat cramps
Painful spasms of leg, arm, or
abdominal muscles
Heavy sweating, thirst
Occur during or after hard work
Loss of body salt in sweat
May be totally disabling
Loosen clothing
Drink lightly salted beverages
Massage76
Rest
Heat Fatigue, headache, dizziness, mus-
exhaustfon cle weakness, loss of coordination,
fainting, collapse
Profuse sweating; pale, moist, cool
skin; excessive thirst, dry mouth;
dark yellow urine
Fast pulse, if conscious
Low or normal oral temperature,
rectal temperature usually
99.5-101.3°F
May also have heat cramps, nau-
sea, urge to defecate, rapid brea-
thing, chills, tingling of the hands or
feet, confusion, giddiness, slurred
speech, irritability
Dehydration, lack of acclimatization;
reduction of blood in circulation,
strain on circulatory system,
reduced flow of blood to the brain
Worker may resist treatment
May lead to heat stroke
Removel to cooler, shaded area as
quickly as possible
Rest lying down
If conscious, have worker drink as
much water as possible
Do not give salt
If unconscious or if heat stroke is
also suspected, treat for heat stroke
until proven otherwise M
Loosen or remove clothing
Splash cold water on body
Massage legs and arms
If worker collapsed, get evaluation
by physician, nurse, or EMT before
worker leaves for the day; shower in
cold water; rest for balance of day
and overnight
Heat stroke
IMMEDIATE
TREATMENT
R60UIRiO
LIFE-THREATENING MEDICAL EMERGENCY
Often occurs suddenly
Headache, dizziness, confusion,
Irrational behavior, coma
Sweating may slow down or stop
Fast pulse, if conscious
Rapid breathing
Rectal temperature 104°F and over
May also have convulsions, nausea,
incoherent speech, very aggressive
behaviour
Sustained exertion in heat, lack of
acclimatization, dehydration, indi-
vidual risk factors (see page 15);
reduced flow of blood to the brain
and other vital organs, body's
temperature-regulating system fails,
body cannot cool itself
Risk of damage to vital organs,
including the heart, brain, central
nervous system, liver, and kidney
Worker may resist treatment
BRAIN DAMAGE AND DEATH CAN RESULT,
EVEN WITH PROMPT TREATMENT
Move to a shaded area
Remove outer clothing/shoes
Immediately wrap in wet sheet,
pour water on and fan vigorously,
avoid over-cooling
Treat shock if present, once
temperature is lowered
If worker vomits, make sure all vomit
is cleared from mouth and nose to
prevent choking on vomit
Transport to nearest medical treat-
ment facility at once
While awaiting or during transport,
elevate legs, continue pouring on
water and fanning
If conscious, have worker drink as
much water as possible
Do not give salt
"Com&nod offsets of heat Illness and pesticide poisoning must be considered with pesticide handlers and "early entry" workers, See "Heat
, „ Bines! and pesticide poisoning," page 7.
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CONTROLLING
HEAT STRESS
MADE SIMPLE
KEY ELEMENTS
1. Water. Make sure workers drink
enough water to replace body
fluid lost through sweating.
2. Acclimatization. Have workers
gradually adjust to working in the
heat.
3. Rest breaks. Have workers take
periodic breaks in a shaded or air-
conditioned area whenever
possible.
4. Monitoring environmental
conditions and workers. Check
temperature and humidity at least
hourly when workers are working
in hot environments and monitor
workers' response to working in
the heat.
BASIC STEPS
• Train workers and supervisors
in how to control heat stress and to
recognize, prevent, and treat heat
illnesses.
• Take into account the weather,
workload, protective gear to be
worn, and condition of the workers.
• Weather. The danger of heat
stress increases with higher temper-
ature and humidity and with direct
Drinking enough water to
replace body fluids lost
through sweating and taking
rest breaks for cooling the
body down are key elements
for controlling heat stress.
sunlight (sun without cloud cover).
The full heating effect of the sun can
equal an increase of up to 13°F in air
temperature. Wind reduces the risk
of heat illness by increasing the
evaporation of sweat when normal
clothing is worn.
« Workload. The body generates
more heat during heavy work than
during light or moderate work.
Applying pesticides on foot gener-
ates more body heat than applying
pesticides from a tractor or truck.
• Clothing and protective equip-
ment. The evaporation of sweat on
the skin helps cool a person. The
more clothes a person wears, the
slower sweat evaporates and the
longer it takes to cool off. Coated
and non-woven synthetic protective
garments effectively block evapora-
tion of sweat. When pesticide
-------
handlers and early entry workers
wear protective garments, they get
hotter than when they wear normal
work clothes.
• The age and physical condition
of the toorkers. Younger workers,
well-rested workers, and physically-
fit workers are less likely to suffer
heat illness than other workers. But
even workers in good shape can
become seriously ill from heat. Many
drugs, including alcohol and cold
and allergy medications containing
antihistamines, increase the risk of
heat illness.
* Whether the workers are used
to working in the heat. Workers who
have gradually adjusted to working
in a warm or hot envkonment are
less likely to become ill.
• Determine minimum amounts
of water workers should drink. (See
Tables 6 and 7, pages 18-19.) Thirst
does not give a good indication of
how much water a person needs to
drink.
• Adjust work practices for the
conditions of each day.
• Schedule heavy work and
•pesticide handling requiring
protective garments and equipment
for the cooler hours of the day
whenever possible.
• Set up work/rest cycles so that
workers work and rest for specific
periods of time. (Tables 6 and 7)
By following these steps, you
will control many heat stress
problems. But you should also be
prepared for times when, regardless
of your efforts, you or your workers
get too hot. When this happens, you
must:
Exposure to pesticides and other toxic agents increases the risk of heat illness.
6
Drinking water
frequently throughout
the work day helps keep
the body hydrated.
Thirst does not give a
good indication
of how much water a
person needs to drink.
• Shorten the length of work
periods and increase the length of
rest periods.
• Give workers shade or cooling
by various means, such as cooling
vests, canopies, awnings, and air
conditioning. Wearing a brimmed
hat to shade the head can be
particularly helpful.
• Reassign workers who are less
fit to lighter work.
• Halt work altogether under
extreme conditions.
Even using these procedures,
some work under certain conditions
will always make workers hot. A
heat stress control program,
however, will help prevent extreme
situations from arising and enable
you to handle those situations
which do arise.
• Give first aid when workers
become ill. Early recognition and
immediate treatment are key to first
aid for heat illness. Mild overheating
and heat exhaustion can quickly
lead to heat stroke, which is a life-
threatening medical emergency.36
Treatment for overheating
includes rest in a cool, shaded area
and drinking plenty of water. Even
-------
after the skin has cooled and a per-
son feels comfortable, internal body
temperature can remain high. Once
a worker has become overheated,
internal body cooling requires 30
minutes or more.
Table 1 on page 4 and Step 8 on
page 32 give more details on the
treatment of heat illness.
HEAT ILLNESS AND
PESTICIDE POISONING
When a pesticide handler becomes
ill from working with organophos-
phate or carbamate insecticides in
warm and hot environments, it can
be hard to tell whether the handler
is suffering from heat exhaustion or
from pesticide poisoning. While
these illnesses share some similar
symptoms, their treatments differ.
Table 2 compares these symptoms.
Combined problems of heat illness
and pesticide poisoning may also
occur. If there is any doubt about
what the illness is, get medical help
immediately. Both pesticide poison-
ing and heat stroke can be life-
threatening and require prompt
treatment.
Shading—with awnings, canopies,
and head coverings—helps reduce
the heat stress from the sun.
Table 2
COMPARISON OF SYMPTOMS OF HEAT EXHAUSTION
AND ORGANOPHOSPH ATE/C ARB AMATE POISONING
Heat Exhaustion
Organophosphate/Carbamate
Poisoning -:-:;
Sweating
Headache
Fatigue
DRY membranes
Dry mouth
No tears
No spit present
FAST pulse (slow if person has fainted)
Nausea
DILATED pupils
Central nervous system depression
Loss of coordination
Confusion
Fainting (recovery prompt)
Sweating ••':
Headache • • :: ',
Fatigue • • .
MOIST membranes
Salivation ' ,: ,<'l-:
• Tears' •'. ;—.':'-:.•"''":•'.'.' ''.•• :,. •
Spit present in mouth
SLOW pulse : ';' : :: r
Nausea and diarrhea :
Possible SMALL pupils
Central nervous system depression
Loss of coordination ;.
Confusion , •'•',•
Coma (can't waken) .-
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A BASIC PROGRAM
TO CONTROL
HEAT STRESS
People vary in size, body temperature, and resistance to
disease, heat, and cold. As a result, heat affects different people
in different ways: some people'can work comfortably at higher
temperatures while others get sick from heat stress.
A heat stress control program
should be geared to protecting all
workers at an establishment, espe-
cially those who are not in the best
physical shape. Table 3 below out-
lines'a basic program for doing this.
Table 3
A BASIC PROGRAM FOR CONTROLLING HEAT STRESS
STEP 1: Assign responsibility for heat stress
problems.
STEP 2: Train workers and supervisors.
» Train workers and supervisors in the control of
heal stress and the recognition, prevention,
and treatment of heat illnesses.
" Conduct safety meetings during heat spells.
STEP 3: Acclimatize workers when they begin to
work under hot conditions.
• Assign a lighter workload for 5-7 days.
• Allow longer rest periods for 5-7 days.
* Assign work in the heat for at least 100
minutes each day.
• Gradually increase the time of work in the heat
each day.
• Watch workers' response to working in the
heat closely for 5-7 days.
STEP 4: Account for the conditions of work and of
the workers.
• Check weather conditions.
» Consider how heavy the work is.
• Consider whether the worker is to wear
protective garments and equipment
» Check if the worker is or has recently been
sick or has had a sharp loss in weight.
• Check whether the worker is rested, is taking
any medications, or appears to have
consumed alcohol that day.
STEP 5: Manage work activities.
• Set up rest breaks.
• Rotate tasks among workers.
• Schedule heavy work for cooler hours.
• Postpone non-essential tasks during heat spells.
• Monitor environmental conditions and workers.
STEP 6: Establish a drinking water program.
STEP 7: Take additional measures, as
appropriate.
• Provide special cooling garments.
• Select lightest weight or "breathable"
protective garments and cooler respirators that
give adequate protection.
• Provide shade.
" Use air-conditioned mobile equipment.
• Modify pesticide usage and handling to reduce.:
need for protective garments and equipment.
STEP 8: Give first aid when workers become ill.
• Set up a first aid program.
• Take heat stroke victims to the nearest
medical treatment facility.
• Follow up on incidents of heat illness.
-------
1
Assign Responsibility
For Heat Stress Problems
Controlling heat stress is the
responsibility of both management
and workers. Government regula-
tions require that employers provide
working conditions that will not
cause illness or death from the
effects of heat, as well as from other
recognized hazards.*
An employer should designate
one person to have principal respon-
sibility for managing the heat stress
program. This helps ensure that heat
stress management will be tended to
continually. Who this person is may
depend on the size of the operation.
At very small operations, the person
responsible for managing a heat
stress program might be the owner
or a specially designated worker. At
larger establishments, depending on
circumstances, this person might be
the owner, a manager, a foreman, a
crew leader, or a person who has
other responsibilities for managing
health and safety. The manager
should be knowledgeable in recog-
nizing, evaluating, and controlling
heat stress.
Managers' duties can include:
• Monitoring environmental
conditions.
• Making work assignments.
• Setting up appropriate work/
rest cycles.
• Adjusting work practices as
necessary.
• Making sure workers drink
enough water.
*29U.S.Code654(a)(l)
• Treating heat stress problems.
• Following up on incidents of
heat illness to prevent their
recurrence.
• Overseeing heat acclimatization
and heat stress training of new
workers. This can include conduct-
ing worker training.
• Conducting periodic safety
meetings during heat spells.
Workers are responsible for:
• Carrying out instructions and
training for controlling heat stress,
including being alert to signs of heat
illness in themselves and others.
• Drinking enough water before,
during, and after work.
• Monitoring their recovery heart
rate, as needed.
• Reporting and responding to
heat stress problems.
• Personal hygiene, not using
drugs, getting adequate rest and
sleep.
I.-/.
Workers need to be
alert to signs
of heat illness in
themselves and others.
Workers are
responsible for drinking
enough water before,
during, and after work.
-------
Train Workers
And Supervisors
Worker and supervisor training
should include:
• The purpose of the establish-
ment's heat stress program.
* The causes, risk factors, and
types of heat illness.
» The establishment's standard
procedures for controlling heat
stress and preventing heat illness,
including:
» Setting work/rest cycles that
account for the weather, work to be
done, and protective garments and
equipment (where required).
» Drinking sufficient water before
work, during breaks, and after work.
• Avoiding the use of alcohol,
illegal drugs, and non-prescription
medications.
• Learning acclimatization proce-
dures and how the acclimatization
process works.
» Taking pulse counts under more
severe heat stress conditions after
the start of rest breaks to measure the
recovery heart rate. A heart rate
above 110 beats per minute after one
minute of rest is an indication of
strain from the heat, that body tem-
perature may be rising, and that
corrective actions, such as shortening
work periods, need to be taken.
» Worker and supervisor responsi-
bilities under the heat stress program.
" Information on heat stress and
its effects, including:
• How heat stress affects judg-
ment, reduces productivity, and
10
Training should
include information on
how heat stress affects
judgment, reduces
productivity, and
increases the likelihood
of accidents and
injuries.
increases the likelihood of accidents
and injuries. This subject should
cover examples of the kinds of acci-
dents which can happen during
work and how loss of judgment
increases the chances of these acci-
dents happening.
• How some things which hap-
pen off the job — such as alcohol and
drug use and failure to drink enough
water or get enough sleep — can
increase the risk of heat illness at
work.
• How to be vigilant and rec-
ognize symptoms of heat ilkiess in
oneself and signs of heat illness
in other workers. People suffering
from severe heat illness, such as
heat exhaustion, may become
unaware of their surroundings,
overactive, uncoordinated, and
mentally confused. Workers suffer-
'ing from heat exhaustion cannot be
expected to be able to take care of
themselves.
• Procedures for first aid and get-
ting emergency medical care.
• (Where applicable) Require-
ments for protective garments and
equipment, how protective gear can
increase heat stress, and additional
measures to control heat stress,
including:
• The protection that protective
garments and equipment give, the
reasons why wearing them is neces-
sary, and the hazards of not wearing
them.
• A frank discussion of how pro-
tective garments and equipment can
be inconvenient and Uncomfortable,
increase the risk of heat illness, and
decrease mobility, vision, and hear-
ing; and a discussion of how to min-
imize these problems.
• Working for shorter periods and
taking longer rest breaks when
necessary, drinking more water, and
using cooling garments.
An employer should conduct
training when a new worker starts
work during warm weather and
conduct full refresher training at the
onset of warm weather each grow-
ing season. During hot weather, an
employer should hold periodic
safety meetings to review and
emphasize procedures for control-
ling heat stress. Periodic checks
•should be done to make sure that
workers understand and are practic-
ing what they have been taught.
-------
3 / Acclimatize Workers
The human body needs time to
adapt to working in the heat. This
adaptation cannot be rushed. It usu-
ally takes about seven days, work-
ing in a warm or hot environment
for at least 100 minutes a day, to
approach full acclimatization to that
environment. Full acclimatization is
achieved after about two weeks.
Table 4 on page 12 gives a summary
of acclimatization procedures.40
Full-time agricultural workers
usually become naturally acclimat-
ized to hot conditions as the
weather gets warmer and usually
need a formal acclimatization period
only when there are sudden
increases in workload, temperature,
humidity, or protective gear that
restricts cooling of the body. Migra-
tory workers may need to acclimat-
ize when they arrive in an area that
is hotter or more humid than where
they last worked. Workers who have
just come from a similar job nearby
may already be acclimatized to
working in the area.
Acclimatization is a process where
the body adapts to levels of work
and heat, improving the stability of
the circulatory system and the bal-
ance of salt in the body. Being in
good physical condition is not the
same as being acclimatized. It
should not be assumed that workers
who are physically fit are necessarily
able to work in the heat easily. But
workers in good physical condition
become acclimatized faster than
workers who are out of shape.M
With acclimatization, a person
working in a warm or hot environ-
ment gains the benefits of smaller
increases in body temperature and
heart rate and of increased sweat
production. Working without accli-
matization greatly increases the risk
of heat illness and work is done
much less efficiently. Acclimatiza-
tion will not reduce, and may
increase, the water requirements of
a worker. Even with acclimatization,
workers may not necessarily work
at higher temperatures and humidi-
ties as effectively as at lower
temperatures and humidities, but
acclimatization allows workers to
work under heat stress conditions
that would otherwise be intolerable
or even fatal.40
An acclimatization period should
be tailored to the type of work, the
type of clothing worn, the climate,
and the worker. A new worker
should start working in the heat for
either two 60-minute periods of light
to moderate work or two 50-minute
Workers who have gradually
adjusted to working In the heat
have less risk of heat illness
and will work more efficiently.
Acclimatization periods
should be tailored to they
type of work, the type of
protective clothing required,
ithe climate, and the worker.
11
-------
periods of moderate to heavy work.
The time of work in the heat should
be gradually increased by about an
hour a day until full acclimatization
is approached. The level of physical
activity should also increase pro-
gressively. The most noticeable
changes in a person's adaptation to
heat occur after the first or second
day of work, but it is important to
complete the full acclimatization
period. During the acclimatization
period, workers should be given
work in cooler environments or a
lighter workload for the balance of
the day.
Some workers may faint during
their first day, but as long as recov-
Table 4
SUMMARY OF ACCLIMATIZATION PROCEDURES
Worker
Status
Heat
Condition
Procedures
Full-time
Gradually warming
None. Acclimatization usually occurs
naturally. Acclimatization procedures
usually needed only for sudden
increases in temperature, humidity,
workload, or level of protective gear.
(See procedures below.)
Full-time Sudden increase
in air temperature,
humidity, workload,
or level of protective
gear
1. Cut work in hotter conditions to Vz
the usual time. For balance of day,
work in cooler environment or lighten
workload.
2. Increase time working in hotter
conditions by an hour each day.
Newly hired,
returning after
not working
for 3 weeks,
or returning
after being
off sick
Warm; protective
gear Is worn
Hot
1. L!ght-to-moderate work: Start work
in the heat for minimum of two 60-
minute periods each day. For balance
of day, work in cooler environment or
lighten workload.
Moderate-to-heavy work: Start work
in the heat for minimum of two 50-
minute periods each day. For balance
of day, work in cooler environment or
lighten workload.
2. Increase time working in the heat
gradually by 1 hour/day until full
acclimatization is approached (aver-
age 5-7 days).
General principles:
* Tailor acclimatization period to the type of work, the type of clothing worn, the
climate, and the worker.
« Start with a lighter workload; increase level of work gradually.
» Start with longer rest periods; decrease length gradually.
• Ctosely monitor workers' response to working in the heat.
ery is prompt, this should not pre-
sent a problem. (See "Fainting or
'Heat Syncope,'" page 33.) How-
ever, if a new worker appears to be
intolerant of heat and experiences
excessive heat strain, consult a
physician.
Once workers become adapted to
working in a warm or hot environ-
ment, they remain acclimatized as
long as they work at least every
fourth day in that environment.
Acclimatization will start to decline
after four days of not working in
that environment, drop significantly
after a week, and be lost totally after
three weeks. Workers who have
been sick or who have not worked
for three weeks need to go through
a full acclimatization period all over
again.
Workers will not be acclimatized
to higher temperatures and humidi-
ties when there is an abrupt rise in
temperature or when the weather
changes from hot and dry to hot and
humid. To become reacclimatized to
the higher temperatures or humidi-
ties, workers need to work in the
more severe conditions for half their
usual time and increase this time by
about an hour a day. (Special mea-
sures to take during heat spells are
given on pages 20-21). °
12
-------
For Each Task, Take into
Account the Conditions of Work
And of the Workers
EVALUATING WORK
ASSIGNMENTS
Whether a worker can perform a
job safely in the heat depends on
the worker's health and level of
heat-acclimation, the difficulty of the
job, the weather conditions on the
particular day, and the kind of pro-
tective garments and equipment
required. Before assigning work dur-
ing warm and hot weather, take into
account:
• Weather conditions. As the
temperature and humidity increase,
additional steps are needed to con-
trol heat stress, such as shortening
work periods, lengthening rest peri-
ods, or reacclimatizing to the higher
temperature and humidity. Further
Work assignments should
take into account the
weather conditions, workload,
necessary protective
equipment or garments, and
the physical condition of
the worker.
-------
precautions are required when the
sun is strong and when there is little
wind or air movement. Heat expo-
sure is most extreme in closed
spaces that absorb heat from the sun
and have poor ventilation, such as
parked vehicles and aircraft, work-
shops, and storage buildings.
Workers will get hotter in direct sun
than under cloud cover.
Current local weather information
generally is available from NOAA
Weather Radio, selected state
weather radio networks, cable tele-
vision weather channels, and private
weather information providers. Cur-
rent temperature and humidity
should be checked at least hourly
when workers are working in hot
environments. Inexpensive devices
for checking humidity are available.
See Appendix I for a list of suppliers
of relative humidity sensors and
indicator cards.
Managers should obtain a climate
profile that includes seasonal
temperatures and their correspond-
ing relative humidities for work
areas where their workers are
exposed to heat. For help, consult
the state climatologist or the
National Oceanic and Atmospheric
Administration Regional Climate
Center. (See Appendix n.) This pro-
file should serve as a guide for
planning when to take measures to
control heat stress.
• The workload. Table 5 lists
various tasks by the approximate
workload involved. The harder the
task, the more heat the body produ-
ces, the hotter a worker gets, and
the more frequently rest breaks are
needed. For many tasks, working
faster increases the workload level.
• Protective garments and
equipment to be worn. Protective
14
garments can be cumbersome and
uncomfortable and make a job more
difficult. Workers who wear protec-
tive garments work harder and get
hotter than they would wearing
regular work clothes.
Protective garments also reduce
the cooling effects of sweat evapora-
tion and of wind. Pesticide handlers
can get very hot very quickly when
they wear respirators/ chemical-
resistant suits, and rubber boots,
hats, and gloves.
• Whether the worker is feeling
well, has recently been sick, or
seems to be losing weight sharply. If
a worker is losing a lot of weight
over a single workday, during the
Table 5
APPROXIMATE WORKLOAD LEVELS
Light.
.Sitting at ease
Writing, typing
Sorting light materials
Inspecting crops
Driving mobile equipment on paved roads
Piloting spray aircraft
Moderate .<...Using a chain saw
Off-road operation of mobile equipment
Periodic handling of moderately heavy materials
Weeding
Hoeing
Picking fruits or vegetables
Air blast and boom spraying
Knapsack spraying on level, even ground
Pushing or pulling light-weight carts or wheelbarrows
Washing vehicles or aircraft
Walking 2-3 rnph
Heavy Transferring heavy materials
Shoveling
Digging
Hand mowing
Loading sacks
Stacking hay
Planting seedlings
Hand-sawing wood
Pushing or pulling loaded hand carts or wheelbarrows
Moving irrigation pipe
Laying cinder blocks
Knapsack spraying on rough ground or on an incline
Walking 4 mph
Very heavy.
..Heavy shoveling or digging
Ax work
Climbing stairs, ramps, or ladders
Lifting more than 44 pounds at 10 lifts per minute
Walking faster than 4 mph, jogging, running
Sources: Reference S9and EPA data.
-------
work week, or from week to week, it
may be due to not drinking enough
water to replace body fluid lost as
sweat.
• Whether the worker is rested, is
taking any medication, or appears to
have consumed alcohol that day.
EVALUATING THE RISK OF
HEAT ILLNESS
Work under hot conditions puts
special stresses on the body. Even
sitting and traveling in the heat for
several hours inside a car without
air conditioning can cause fatigue or
exhaustion. People with the follow-
ing characteristics are often more
sensitive to heat:
* very small body size
' poor nutrition
m overweight
m poor physical condition
u lack of heat-acclimatization
B increasing age over 40
* previous heat illness (except
heat cramps)
* heart disease, high blood
pressure
H diabetes
a skin disease
a liver, kidney, and lung
problems
Medical examinations can help
identify workers with special risk of
heat illness. Pre-placement and
annual or more frequent followup
examinations are recommended. A
physician should provide a written
opinion to the employer and to the
worker about the worker's fitness to
work in the heat. For more details
about medical examinations, see
Reference 5.
When working in warm and hot
environments, the following factors
generally increase the risk of heat
illness:
• Environment:
* lack of air movement
* temperatures above 70°F (80°F
at night)
m direct sunlight
m humidity
m exposure to any toxic agent, in-
cluding pesticides
• Job:
* heavy work
* prolonged shifts
Individual response to working
in the heat can vary greatly.
!• Clothing and Protective Gear:
IB thicker clothing; more than one
layer of clothing; tight clothing;
stiff clothing; darker colors of
| clothing
M chemical-resistant garments
and respirators
II Physical Condition and Personal
Habits:
M failure to drink sufficient water
i before work, during breaks, and
after work
BI lack of acclimatization
BI late stages of pregnancy
ii general fatigue, lack of sleep
if diarrhea, vomiting
• dehydration
• infections
» fever
dizziness, lightheadedness
B sunburn, skin rash
" recent illness or injury
recent immunization or
inoculation
low salt diet
malnutrition
s sleeping pills and medications
which limit sweating, such as
atropine, scopolamine, antihist-
apines, some tranquilizers, cold
medicines, some anti-diarrheal
medications, and certain other med-
ications (such as blood pressure
medicine, diuretics, water pills, or
amphetamines)
« use of illegal drugs
*| excessive consumption of caffeine
" alcohol consumption during the
previous 24 hours
| Alcohol lowers tolerance of heat
and increases the chances of devel-
oping heat stroke. Hangover does
the same. Workers should not drink
any alcoholic beverages before start-
ing work or during the workday.
V2,30,39,66
15
-------
Manage Work Activities
Employers should include the fol-
lowing approaches for managing
work in their heat stress control
program:
» Setting up rest breaks.
• Rotating tasks.
• Shifting times for doing heavy
work and work requiring protective
gear.
" Reducing workloads.
• Postponing non-essential tasks.
These measures go against some
traditional notions about work and
productivity. But as part of an over-
all heat stress control program, these
measures help protect employee
health and help maintain worker
efficiency and safety. Heat stress
control programs are now standard
in many industries and the armed
forces.
SETTING UP REST BREAKS
Workers recover from the heat
more effectively with shorter, more
frequent rest breaks than they do
with longer, less frequent breaks.
Longer, frequent rest breaks are
necessary for heavier work and for
work in higher temperatures and
humidities. Rest breaks should be
promoted among workers as a time
for drinking water. Whenever possi-
ble, rest breaks should be taken in a
shaded or air-conditioned area. It is
hard to rest effectively in a hot
environment. Rest breaks help
workers recover from heat because:
» The heart rate slows.
• The body cools down.
" Body fluids lost from sweating
are replaced with drinking water.
16
Under mild conditions, workers
wearing protective gear might take a
ten-minute break every hour. When
heat stress conditions increase, a
(Text continues on page 20)
As heat stress conditions
increase, rest breaks should
become more frequent
-------
GENERAL PRINCIPLES FOR SETTING WORK/REST PERIODS
1 Tables 6 and 7 on pages 18 and 19 and these general
principles together provide an approach for setting
work/rest periods. Individual requirements may vary
greatly. The work/rest periods in these tables are not a
guarantee of protection against heat illness and should
not be used as a substitute for good judgment and
experience. These tables apply to healthy, acclimatized
adults under the age of 40. They do not apply to
children.
2 Managers should obtain and use Agricultural
Weather Service/state climatologist climate
profiles of work areas where their workers are exposed
to heat as a guide for when to institute methods for
controlling heat stress.
3 Trained supervisors should oversee work and
rest periods and check temperature and [Table 6
only] relative humidity at least hourly when workers
are working in hot environments. On a sunny day, the
relative humidity will typically drop as the temperature
rises. In greenhouses, higher humidities and the
reduced heating effect of the sun should be accounted
for when scheduling work/rest periods.
4 Shorten work periods and increase rest periods
and water consumption:
• for heavier work.
" as temperature rises.
• as humidity increases [Table 6 only].
• when protective clothing or equipment is worn
[Table 6 only].
• as the sun gets stronger (late morning through early
afternoon).
• When there is no air movement, such as work in an
enclosed space [Table 6 only].
C Shorten work periods and increase rest periods
for children and pregnant women.
Adjust work/rest periods to other
tions of work and of the workers.
6 Adjust work/rest periods to other specific condi-
ti
7 Breaks for cooling down should not be cut short.
These breaks are necessary to slow down the
heart rate and cool down deep body temperature. (This
is not the same as skin temperature.) Feeling cooler is
not in itself a good indication that deep body tempera-
ture has dropped and that the heart rate has slowed
down sufficiently.
As conditions become more severe, check the
recovery heart rate after one minute of rest by counting
the pulse. Place the index and middle fingers on the
opposite wrist below the thumb. Count the pulse for 30
seconds. If the rate is over 55 beats (110 per minute),
shorten the next wdrk period by one-third. "•u'">
I
8 New and unacclimatized workers should be
assigned lighter wo>rk and longer rest periods and
be monitored more closely.
9 [Table 6 only] Account for weather conditions by
adjusting the temperature reading as foDows
before going to the temperature column in the table:
" If there is full sun1 (no clouds) add 13°
If the sky is partly cloudy/overcast add 7°
If no shadows are1 visible or work
is in the shade or at night no adjustment,
• For relative humidity of:
10% subtract 8°
20% ! subtract 4°
30% > no adjustment
40% » % add 3°
50% ! add 6°
60% add 9°
For example, if the temperature is 91°, it is dusk, the
relative humidity is 40%, and heavy work is to be done,
such as moving heayy materials with a wheelbarrow:
Start with 91° ar^d add 3° because the humidity
is 40% [91°+3°=94°]. Go to 94° in the table.
r
Under these conditions, it would be reasonable to
follow a normal woirk schedule.
On the other hand, if the temperature is 85°, it is midday
with no clouds in the sky, the relative humidity is 50%,
and heavy work is to be done, such as unloading a
wagon of hay: I
Start with 85°, aidd 13° for the additional
heating effect of the sun, and add another 6°
because the huinidity is 50% [850+13°+6°=1040].
Go to 104° in the table.
i
Under these conditions, it might be necessary to work
approximately 20 minutes and rest 40 minutes during
the course of each hour that this task is done. It would
be better, if circumsttances permit, to shift this task to
a time when it is copier or the sun is not so strong, in
order to reduce heat stress and avoid the need for
longer rest periods..
17
-------
APPROACHES FOR SETTING WORK/REST PERIODS
TO USE TABLE 6
You will need the following
information:
• the current air temperature.
• the current relative humidity.
• an estimate of sunlight (full, partly
cloudy/overcast, or no shadows
visible).
* an estimate of the workload (light,
moderate, or heavy). (See Table 5,
page 14.)
1. Read through the general princi-
ples on page 17.
2. Adjust the current air tempera-
ture reading, if necessary, to account
for the amount of sunlight and the
current relative humidity (see item
9, page 17). Two examples are
included with the general principles
in item 9.
For work in hotter temperatures
when the relative humidity is at or
above 70%, use Table 7. Work under
these conditions is roughly compar-
able to work in chemical-resistant
clothing.
3. Go to Table 6, find the adjusted
temperature reading, and read
across to the column matching the
workload. Remember that these
work/rest times are only part of an
overall approach and that individual
requirements will vary greatly.
Table 6
APPROACH FOR SETTING WORK/REST PERIODS
AND AMOUNT OF DRINKING WATER FOR WORKERS WEARING
NORMAL WORK CLOTHING*
Air
Temperature
Light
Work
Moderate
Work
Heavy
Work
Minimum
Water
to Drinkt
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
45/15*
40/20
35/25
30/30
15/45
Caution**
Caution**
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
45/15*
40/20
35/25
30/30
30/30
25/35
20/40
15/45
Caution**
_ Caution**
Caution**
Caution**
Caution**
Normal
Normal
Normal
Normal
Normal
45/15*
45/15
40/20
35/25
35/25
30/30
30/30
25/35
20/40
20/40
15/45
Caution**
Caution**
Caution**
Caution**
Caution**
Caution**
Caution**
\/
1/a pint
every
30 minutes
1/a pint
every
15 minutes
Vs. pint
every
10 minutes
IMPORTANT NOTE: The general principles on page 17 must be followed when using this table
Adjustments to temperature must be made for higher humidities and heat from the sun.
"This table is based on American Conference of Governmental Industrial Hygienists limits for heat-
acclimatized adults. Assumptions include physically fit, well-rested, and fully hydrated workers under
the age of 40; adequate water intake; 30% relative humidity; natural ventilation with perceptible air
movement; and air temperature readings in Fahrenheit, taken in the shade, no sunshine or no shad-
ows visible. (National Weather Service temperature readings are also taken in the shade.) See Appen-
dix III for the method for deriving this table. Sources: ACGIH, Threshold Limit Values10'" and NIOSH
Occupational Exposure to Hot Environments.5 '
fVaries from person to person and increases with heavier work and hotter conditions At higher
temperatures, there are limits to how long heavier work and consumption of large amounts of water
can be kept up; continue water consumption after work to replace all lost body fluids Source- US
Army, "Heat Injury Prevention." GTA 8-5-4S23 '
$45/15 minutes = 45 minutes work and 15 minutes rest during each hour.
^Indicates very high levels of heat stress.
18
-------
TO USE TABLE 7
You will need the following
information:
• the current air temperature.
• an estimate of sunlight (full, partly
cloudy/overcast, or no shadows
visible).
• an estimate of the workload (light,
moderate, or heavy). (See Table 5,
page 14.)
1. Read through the general princi-
ples on page 17.
2. Go to Table 7, find the current air
temperature, and read across to the
column matching the workload and
the amount of sunlight. Remember
Ithat these work/rest times are only
part of an overall approach and that
individual requirements will vary
greatly.
Table? . ;,
' ' * 1— • — - — • - * >"> i *.*••> if* * *** -i-l^M t, J i, % ,
APPROACH FOR SETTING WORK/REST PERIODS AND AMOUNT OF DRINKING WATFR
FOR WORKERS WEARING CHEMICAL-RESISTANT SUITS* *
Air
Temperature
75°F
80°F
85°F
90°F
95°F
-Light Work-
Partly
Full Sun Cloudy No Sun*
Normal Normal Normal
schedule schedule schedule
30/30 Normal Normal
schedule schedule
15/45 40/20 Normal
schedule
Caution** 15/45 40/20
Stop Stop 15/45
work work
Work/Rest Periods
-Moderate Work-
Partly
Full Sun Cloudy NoSunf
Normal Normal Normal
schedule schedule schedule
20/40 Normal N0rmal
schedule schedule
10/50 25/35 Normal
schedule
Caution" Caution** 25/35
Stop Stop Stop
work work " work
«u
— HJS.J vy Work—
f Partly
Full Sun i Cloudy NoSunt
35/25$$ 4 Normal Normal
^schsiidule^ schedule
' 10/50 [ 40/20 Normal
"l schedule
Caution** {j5'45 40/20
Stop 'Caution** 15/45
work "J
TU.*" '
6top i Stop Stop
work t work work
Minimum
Water
to Drink'f
One half pint
every 30 minutes
One to 11/2 pints
every 30 minutes
One pint or more
every 15 minutes '
Same as above
Same as above
uTng S,eN°TE: ^ **"* ^^ °" P39e 1 7 mUSt be followed when Caries from person to person «jd increases w.th heavier work and hotter
.T, ...... J conditions. At higher temperatures, there are limits to how long heavier work and '•
mis table is based on values for heat-acclimatized adult workers under the aqe of consumption of large amounts of water can be kept up: continue water consumotion '
40 who are physically fit, well-rested, and fully hydrated; with the assumpations of after work to replace ail lost body fluids. H
tNoshadowsarevisibieorworkMnmeshadeoratnight. ' i
to work for longer periods. Adjustments must be made when additional protective #35/25 » 35 minutes work and PS minutes rest each hour
gear ,s worn. See Appendix Hi for the method for deriving this fable. "Indicates very hiah levels of yJt •*»*«
= — — sasi. .. , " ,£ * ." ! v ° j H J^'-i ^H*>^^ •& * j-t
Source. Ralph F. Goldman, Internal Report: Heat Stress Management Protocol, Office of Research and Development, U.S. EPA, November 1 9897
Tables 6 and 7 are methods for approximating a technical index called Wet Bulb Globe Temperature (WBGT) which combines the effects of JiiimJH
19
-------
-
Do not allow workers to push
themselves or to be pushed to
keep on working when they
begin to feel ill from the heat
Supervisors should insist that
workers take the time
necessary to cool down.
(Continued from page 16)
five-minute break every half hour
would be better. When workers
work in chemical-resistant suits
and/or in higher temperatures and
humidities, the length of rest breaks
and the amount of water they drink
must increase sharply.48(See Tables
6 and 7 and "general principles" on
pages 17 to 19 and Step 6 on page
22.) For situations where taking off
protective gear and putting it back
on may increase exposure of
workers to pesticides, cooling gar-
ments can reduce the need for
breaks. (See pages 26-27.)
Work/rest cycles should be flexi-
ble. Even among acclimatized
workers, there are large individual
differences in work capacity and tol-
erance to heat and this tolerance can
vary from day to day.MMany per-
sons are able to work under hot
conditions for longer periods than
those given in Tables 6 and 7; for
others, these work periods may be
too long.
It is more important that supervi-
sors understand the trends and
underlying principles of these tables
than that they follow work/rest
times exactly. The first "general
principle" on page 17 is especially
important and merits stating here as
well:
The suggested work/rest periods in these
tables are not a guarantee of protection
against heat illness and should not be
used as a substitute for good judgment
and experience.
People naturally want to perse-
vere and finish a task at hand. In
agriculture in particular, the
demands of crop production and
pest control during warm and hot
weather create pressure to get as
much done in as short a period as
possible. In addition, workers and
employers often face strong eco-
nomic pressure not to interrupt
work.
Do not allow workers to push
themselves or to be pushed to keep
on working when they begin to feel
ill from the heat. Supervisors should
insist that workers take the time
necessary to cool down. Under
extreme circumstances, it may be
necessary to stop work altogether,
unless cooling garments are used.
"Toughing it out" is dangerous.
Workers are in danger of becoming
seriously ill or dying when either
they or their supervisors fail to rec-
ognize the need for breaks to cool
off under heat stress conditions.
With heat exhaustion and heat
stroke, the flow of blood to the brain
decreases and mental function
becomes impaired. A worker will
become less aware of his or her con-
dition and may become aggressive,
try to work harder, and resist being
told to stop work. There have been
fatalities where workers pushed
themselves harder at the very time
they should have been forcibly
stopped from continuing to work.
ROTATING TASKS
When possible, rotate heavier
tasks among workers in the best
physical condition and alternate
heavy work with light and medium
work.
20
-------
SHIFTING TIMES
FOR CERTAIN ACTIVITIES
When possible, schedule heavy
tasks and work requiring protective
gear for cooler hours of the day,
such as in the early morning or at
night, but be aware that cooler, early
morning temperatures can mislead
some workers to think that heat
stress will not occur under these
conditions. The relative humidity is
usually highest at this time. Very
high humidity limits evaporation of
sweat, even at cooler temperatures.
This can prevent adequate cooling of
the body and lead to serious heat
illness. When the relative humidity
is above 70%, heavy work can be
particularly risky. Workers should
still be alert to heat strain, take rest
breaks to cool down, and drink
enough water to replace body fluid
lost from perspiration.12
POSTPONING
NON-ESSENTIAL TASKS
DURING HEAT SPELLS
With unusually hot weather last-
ing longer than two days, heat can
build up in the environment both at
work and at home, and the body can
become progressively dehydrated.
Chronic dehydration can occur
without any signs of thirst; in its
early stages it may be indicated by a
lack of alertness. During heat spells,
increase water consumption both on
and off the job and postpone non-
essential tasks likely to cause severe
heat strain until after the heat spell
is over. For tasks which cannot be
postponed, special measures should
be taken, such as:
• Establishing sharply limited
work periods.
• Restricting overtime work.
™ Monitoring workers closely for
heat stress.
• Wearing cooling garments. (See
Step 7, page 26.)
• Assigning heavy tasks only to
workers who are in good condition
and are fully acclimatized.
• Conducting safety meetings to
emphasize special heat spell
procedures.
CHILDREN
Special efforts should be made,
through training and supervision, to
protect children working in hot
environments. When doing similar
work in hot environments, pre-
adolescent children generate more
heat for their body weight than
adults and, at the same time, their
bodies do not sweat as much. As a
result, children tend not to cool off
as quickly and have a lower toler-
| ance for work in very high tempera-
tures.76
Child workers need to take longer
i rest breaks, work fewer hours per
day, work fewer days per week, and
be strongly directed to drink ade-
quate amounts of fluid. Children
should be given extra supervision
because their judgment is different
from that of adults. Child workers
I also should be strongly encouraged
to be alert to symptoms of heat
illness in themselves and not to take
risks I5-16'21'25-56-65
During heat spells, special measures should be taken,
such as postponing non-essential tasks and monitor-
ing workers closely for heat stress.
21
-------
Establish A Drinking Water Program
DEHYDRATION
Dehydration is a primary cause of
heat illness. Replacing body fluid
lost in sweating is the single most
important way to control heat stress
and prevent heat illness.
Dehydration has several notable
effects:
» Reducing skin cooling. The
principal way the body cools itself is
through the evaporation of perspira-
tion. Dehydration results in less
body water being available for
sweating and reduces the body's
ability to disperse heat by evapora-
tion of sweat.
• Straining the circulatory sys-
tem. The body contains about five
quarts of blood, composed mostly of
water. When a worker starts to
perspire during work in the heat,
the rate of circulation increases.
Blood also helps cool the body by
moving heat produced by the
muscles outward to the skin for
release into the air.
When dehydration occurs, the
blood flow needs of the skin and
active muscles are not met. The
SiXGALWNS THISI57HE
CFWieRA P&SBKT.
WY? THAT CORPORAL!
TO F£ND OFF H5AT DISORDER.,
YOU GOTTA WPRAT&! SIX.
6AUONSA PAY—THAT'S
24 QPTHese Barnes r
mHOff CONSTANT WATER INFU-
SION, YOU'f&P5APMgAT-YOU
D5HYDRAT& IN A BLINK! WATER
I5&VBRYTH1N6 HSR5, ITS THB
"
THAT BREAKS DOWN 70
96 EIGHT-OUNCE GLASSES
A PAY, ORON& GLASS
&VZRY TBNMINUT5S FOR
16 HOURS
„ A PAY!
BBTTBR UM...WHAT I'LL.
6&T IFW&R& COVZR
. ATTACKED* YOU
This carkxm appeared doting Operation Desert Shield. Despite the humorous treatment given here, the U.S. Army viewed water to be as important as ammunition in logistics
ptarmmg and as the primary tool for maintaining individual performance, health, and hygiene in the desert heat.
DOONESDURY copyright 1990 by G.B. Trudeau. Reprinted with permission of UNIVERSAL PRESS SYNDICATE: All rights reserved.
22
-------
•Under very severe heat stress
conditions, a person can sweat up
to two quarts per hour. Workers
ijieed to be reminded constantly of
their need to drink water and be
directed to drink "by the clock."
body produces less sweat and
becomes overheated from work. A
lack of alertness may indicate early
stages of dehydration. Additional
effects of dehydration include mus-
cle exhaustion, lower performance,
clumsiness, dehydration of body
tissue, and less blood being pumped
by the heart with each beat. Severe
dehydration can result in death.
DRINKING WATER AND
FLUID REPLACEMENT
The amount of drinking water
necessary to replace water lost as
sweat and prevent dehydration var-
ies with each person and is affected
by temperature, humidity, and work
being done. The idea that a person
can become like a camel and adjust
to working in the heat with less
water is strictly a myth. Estimates of
water requirements for persons
doing moderate work in temperate
regions during the summer range
from six to ten quarts per person per
day. On a hot day, it is possible for a
worker to lose as much as three
gallons of perspiration. At low
humidities, a person can be sweat-
ing heavily and still have dry skin.
Most protective garments limit
sweat evaporation (but not sweat
production) and chemical-resistant
suits can cause rapid dehydration if
sweat is not replaced. Under very
severe heat stress conditions, a per-
son can sweat up to two quarts per
hour, but this rate of sweating can-
not be tolerated for long.
As a general principle, workers
should drink enough water to
replace all body fluid lost through
perspiration. Put another way, work-
ers should drink enough water to
maintain their normal body weight
throughout the day. A sharp loss in
weight is an indication that a worker
has not been drinking enough
water. Other indications are dark
yellow urine and passing less urine
than usual. Having workers weigh
in each morning on a bathroom
scale is a simple way to check for a
sharp loss in weight.
Workers need to be reminded con-
stantly of their need to drink water.
When they are very busy, they will
be prone to drink even less. Thirst is
not a good way to know how much
water a person needs to drink, nor is
satisfaction of thirst an indication
that body fluids have been replaced.
Workers who have plenty of drink-
ing water available but only drink to
satisfy their thirst will drink about
two- thirds the amount of water their
bodies need. This can result in a net
loss of one to two quarts of body
fluid (two to four pounds of body
weight) on a hot day. Chronic dehy-
dration can develop gradually over
several days and occur without any
signs of thirst. It can lead to severe
medical problems, such as constipa-
tion, piles, kidney stones, and uri-
nary infections.76
!ln general, when workers work in
hot environments, they should be
directed to drink "by the clock,"
at least one cup of water every 30
minutes and greater amounts as
conditions become more extreme,
even if they are not thirsty. It is
easier to drink smaller amounts of
water frequently than it is to drink
larger amounts less often. Drinking
two or three cups of water before
work gives a head start. Expe-
rienced, acclimatized workers and
supervisors who have not pre-
viously followed a rigorous drinking
water schedule may be surprised
at the reduction of strain from the
heat.75
23
-------
Under severe heat stress condi-
tions, such as heavy work in high
temperatures or work in encapsulat-
ing clothing at temperatures above
70°F, workers should be scheduled
and directed to drink a pint or more
of water before starting work and
enough additional water throughout
the day to replace all sweat lost.
They should also be encouraged to
drink ample quantities of water after
work, through the end of the eve-
ning meal.
Caution: Persons with epilepsy or
with heart, kidney, or liver disease;
persons who have fluid-retention
problems; and persons who are on
restricted fluids should consult a
physician before increasing the
amount of fluid they drink.M
Supervisors should be alert to
workers who, because of economic
pressure, deliberately limit
the amount of water they drink in
order not to have to stop work to
urinate. Older men with prostate
problems and some women may
also limit the amount of water they
drink when a private toilet is not
readily available. Where these prob-
lems occur, employers need to
address these concerns to make sure
that these workers will drink
enough water. Under hot conditions,
drinking a lot of water does not
cause an increase in urine, provided
that excessive caffeine has not been
consumed.
Supervisors should remind work-
ers that not drinking enough water
can lead to heat exhaustion and heat
stroke and that avoiding urinating
can lead to other severe medical
problems. Supervisors should also
stress how drinking ample water
helps one to stay productive and
maintain well-being in the heat.
24
Preferable water
temperature is
between 50° and GOT.
Most people tend not
to drink warm or very
cold water in quanity
as readily as they
will cool water.
OSHA's Field Sanitation Stan-
dard* sets minimum requirements
for drinking water, which should be
followed throughout agriculture.
OSHA requirements include:
• Providing sufficient amounts of
suitably cool, potable water. On
average, a total of two to three gal-
lons per worker on a hot day should
be enough, but specific needs will
vary. Preferable water temperature
is between 50° to 60°F. Most people
tend not to drink warm or very cold
water in quantity as readily as they
will cool water.
• Providing single-use drinking
cups or water fountains. Individual
canteens or sport bottles may be
more suitable for some situations.
The use of common drinking cups or
dippers is prohibited. People tend to
drink more water from cups and
containers than they do from water
fountains.
• Providing water that meets
water quality standards. Water
must meet either state standards,
local standards, or standards
under the U.S! EPA's "National
Interim Primary Drinking Water
Regulations"**
• Placing water in locations
readily accessible to all employees.
Drinking water should be located as
close as possible to where workers
are working (but .protected from con-
tamination by pesticides) so it can
be drunk whenever it is needed.55
Workers should be directed only
to drink safe drinking water. Some
workers believe that they can drink
irrigation water and need to be told
that'irrigation water can contain
pesticides and fertilizers.73
SOFT DRINKS
Flavored beverages are desirable
if workers will drink them in large
quantities. Avoid beverages high in
sugar or salt content. Carbonated
soft drinks are not recommended as
a primary beverage for replacing
body fluid because the gas makes
them difficult to drink in large quan-
tities. Dilute iced tea or lemonade
are good alternatives if the sugar
content is kept low. Unfortunately,
drinks which "cut" thirst also dis-
courage adequate fluid replacement.
29,55,69
ALCOHOL
Drinking alcohol while working in
the heat should be prohibited. Alco-
hol affects the body's temperature-
regulating capacities and increases
the risk of heat illness. Every heat
stress training program should
emphasize the hazards caused by
alcohol. Workers should be strongly
urged not to drink any alcohol dur-
ing hot weather before starting work
and until the end of the evening
* 29 Code of Federal Regulations 1928.110
**40 Code of Federal Regulations 141
-------
meal after work in order to give
their body a chance for full replace-
ment of all lost fluid.
SALT AND OTHER
ELECTROLYTES
A balanced diet usually contains
enough salt, even during the hottest
weather. If a worker's diet is lacking
salt, consult a physician about what
to do. Routine addition of salt can
lead to dehydration. A heavy salt
diet may interfere with acclimatiza-
tion and contribute to heat illness.x
Salt tablets should not be used.
Persons who have heart problems
or who are on a "low salt" diet
should consult a physician about
their working under heat stress
conditions.
Heavy work in the heat can lead
to a loss of glycogen (a type of
; carbohydrate) from the liver and
muscles and a loss of electrolytes, in
addition to a loss of water in the
body. Some scientists believe that
electrolyte-carbohydrate beverages
may be of benefit when workers do
heavy work in the heat for more
than one hour. Commercial
electrolyte-carbohydrate products
are not all formulated identically.
Some ready-to-drink formulations
are too concentrated and need to be
!diluted. Some contain too much
sugar. Employers electing to provide
these beverages should ask suppli-
ers for electrolyte-carbohydrate
products that have a content similar
to what the Food and Nutrition
Board of the National Academy of
Sciences Committee on Military
Nutrition Research recommends*
and that their workers find tasty.76
* Technical Note: While the use and formula-
tion of these products bear further evaluation,
the Food and Nutrition Board of the National
Academy of Sciences Committee on Military
Nutrition Research has recommended that
these "solutions should provide approxi-
mately 20 to 30 meq [milli-equivalents] of
sodium per liter, 2 to 5 meq of potassium per
liter, and chloride as the only anion. The
carbohydrate content should be provided as
glucose or sucrose malto-dextrin, or other
complex carbohydrate in a concentration of
5% to 10%." 31
Drinking water must be
readily accessible.
25
-------
Take Additional Measures
PROBLEMS FROM
PROTECTIVE GARMENTS
Pesticide handlers and "early
entry" workers are required to wear
protective gear for many pesticides.
This can present a conflict between
protection against pesticide expo-
sure and avoiding heat stress. The
very weight of some garments and
respirators can increase the amount
of heat the body produces.
SPECIAL COOLING
GARMENTS
One way to slow the buildup of
heat when wearing protective gear
is to use special cooling garments,
such as cooling vests, which are also
known as "ice" vests. UHW7° Cooling
garments:
* Let workers work harder,
longer, and more comfortably in the
heat.
• Lower skin temperature.
" Reduce the risk of body
dehydration.
« Reduce the need for frequent
water breaks.
• Reduce the frequency that pro-
tective gear needs to be taken off.
Cooling vests have the disad-
vantages of extra bulk and weight,
limited time of use, and the need to
store coolant packets. Nevertheless,
cooling vests are one of the most
effective ways for workers, espe-
cially pesticide handlers and early
entry workers who wear chemical-
resistant suits, to work comfortably
26
and productively in the heat with
reduced heat stress. Cooling vests
are now used extensively in the
nuclear power, chemical, and steel
industries and in space exploration.
Care should be taken to avoid
too much cooling. Effects can
include reddening of the skin. When
workers are hot and sweaty, cooling
vests may feel uncomfortable when
they are first put on.14
Some vests are too cold to wear
directly against the skin. While one
or two layers of clothing worn
underneath the vest should take
care of this, pilots and mobile
equipment operators may need to
wear three layers because of the cold
pressure against their back from the
back of the seat..14
Persons with a short trunk of the
body may need to remove the bot-
tom row of coolant packets to make
it easier to bend over.14
COOLING VESTS AND
CHEMICAL-RESISTANT SUITS
Workers will not want to wear
cooling vests unless working
without them is uncomfortable or
intolerable.
• Below 70°F. Workers should
not need cooling vests unless they
are doing heavy, sustained work.
• Above 70°F. Cooling vests may
be useful when pesticide handlers
are wearing chemical-resistant suits
and are either doing heavy work or
doing moderate work for a pro-
longed period.
• Above 80°F. Working in chemical-
resistant suits for more than a half
hour without taking frequent water
and rest breaks is unsafe. Special
measures, such as wearing cooling
garments, are recommended and work-
ers should take frequent breaks. (See
Table 7, page 19.)
The effectiveness of cooling vests
drops as their coolant packets
become warmer. Workers wearing
cooling vests should take rest
breaks combined with scheduled
water breaks when the coolant
packets need changing. There is
danger of contaminating the skin
each time a protective garment con-
taminated with pesticides is opened
and closed or taken off and put back
on. The longer a worker can work
safely in a protective garment before
needing relief from the heat, the
safer overall the worker will be.
-------
Rotofs can shade
pesticide mixing stations.
SELECTING
COOLING VESTS
Cooling vests should be selected
with care. Recommended features
include:
• Snug fit, hanging from the
shoulders and extending below the
waist to hip level.
• Effective exterior insulation.
• Comfortable fabric with good
water absorption and retention,
such as cotton.
• Flexibility and minimum bulk
for easy movement.
These features maximize contact
between the trunk of the body and
the vest, provide greater cooling,
and minimize interaction of the
trunk of the body and coolant
packets with environmental heat.
See Appendix I for a list of suppliers
of cooling garments.
MAINTAINING
COOLING VESTS
Vests should be washed fre-
quently to remove body odor —
daily if more than one worker uses
the same vest or if the vest is worn
under protective garments for han-
dling pesticides. Coolant packets
should be discarded when their
seams open or they are punctured.
OTHER
COOLING GARMENTS
Cooling systems which deliver
cool air or pump ice water to special
garments worn by a worker may be
useful in some situations. For a list
of suppliers of these systems, see
Appendix I.
SELECT LIGHTER WEIGHT
PROTECTIVE GEAR
AND COOLER RESPIRATORS
Wearing lighter weight clothing
and gear reduces the amount of heat
the body produces. Light color
clothing absorbs less heat from the
sun than darker clothing. Whenever
possible, use the lightest weight pro-
tective garments and respirators
that give adequate protection.
Powered air-purifying respirators
and supplied-air respirators gener-
ally feel cooler than other types of
respirators because breathing resist-
Brinnmed hats help shade
the head and eyes.
27
-------
Awnings provide shade »
over open mobile equipment |
ance is minimized and the airstream
has a cooling effect.
SHAPE
Shade gives relief from the heat of
the sun. Canopies, sunshades, and
umbrellas can provide shade to
open mobile equipment. Canopies
are also helpful over pesticide mix-
ing stations. The benefits of wearing
brimmed hats and sunglasses for
shading the head and eyes should
also not be overlooked. Whenever
possible, workers should spend rest
periods in a shaded area not contam-
inated with pesticides. With open
field conditions, tarpaulins tied to
four posts can provide shade where
no other shade is available.
AIR-CONDITIONED CABS
ON MOBILE EQUIPMENT
Enclosed air-conditioned cabs on
mobile equipment reduce exposure
to heat, the need for protective gear,
AJr-cond'taed cabs on mottle equipment reduce
exposure to heat and pesticides.
28"
and pesticide exposure to an appli-
cator. Air conditioning filtration
systems should be appropriate for
the pesticides used.
MODIFYING PESTICIDE
USAGE AND HANDLING
Under many circumstances, grow-
ers can consider modifying growing
practices and use integrated pest
management programs to reduce or
eliminate the need for highly toxic
pesticides which require protective
garments and respirators. Even
where growing practices are not
modified, applicators may be able to
substitute pesticides of lower toxic-
ity for those which require protec-
tive gear. Totally closed pesticide
mixing systems can also reduce the
need for protective gear. Technical
help on growing practices and selec-
tion of pesticides can be obtained
from cooperative extension services.
PROTECTING PILOTS
The risk of heat strain among
agricultural pilots is particularly
high because cockpits become
heated in the sun, even during mod-
erate weather, creating what has
been called a "greenhouse effect."
Inside cockpit temperatures can rise
well above the outside air tempera-
ture. Some levels of heat stress
normally endured by ground
workers can be dangerous in pilots.
Even subtle changes in psychomotor
performance and neurobehavioral
function caused by mild heat strain
affect a pilot's judgment and ability
to fly safely. Fatigue is a basic
concern with pilot safety and is
compounded with exposure to heat.
Heat and dehydration also lower
pilot tolerance of acceleration (G)
stress 18/ ^47'48/ 49/ 50/ 52< 53' ^63> 73
Agricultural pilots are subject to
additional hazards beyond those
faced by ground workers. Low-level
flying demands that pilots devote
their maximum concentration to
conditions outside the cockpit. They
often fly near telephone and power
lines and poles, and make scores of
180° turns each day.3462
Heat and sweat — especially
sweat dripping from the forehead
into the eyes which can cause the
eyes to have painful spasms — are
uncomfortable and distracting, and
decrease pilot alertness. Sweatbands
-------
are helpful for keeping sweat out of
the eyes.51
Minor effects from even very low
exposures to certain classes of pesti-
cides, such as organophosphates and
carbamates, can also result in
impaired judgment in flying and play
a role in agricultural aircraft acci-
dents. The interaction of mild heat
strain and low-level exposures to pes-
ticides may be even more detrimental
to pilot safety. People are often
unaware of these minor effects, mak-
ing this danger worse. ^26'48'52-6I-62- ^ «•«
It is essential for safe aircraft
operation that pilots fly at peak
efficiency. Heat stress problems in
agricultural aviation are similar to
those with military aircraft flying at
low altitudes. The Indexes of Ther-
mal Stress for Hot Weather Aircraft
Operation are used in military
aviation and may be useful in agri-
cultural aviation. (Tables 8 and 9 on
page 31.) Pilots should avoid heat
stress from exposure to heat before
and between flights and from physi-
cal exertion. ^
In aircraft without air condition-
ing, there should be a thermometer
placed out of direct sun for measur-
ing inside cockpit temperature. At
the present time, probably the most
effective ways to counter hot cock-
pit conditions in places where there
are long, sustained periods of heat
are to wear cooling garments and fly
during hours when the sun is not
strong or, where possible, to install
aii' conditioning if the cockpit is
closed. The air conditioning system
should be of a design that prevents
pilot contamination.
Cockpit air conditioning systems
present a tradeoff in how horse-
power is used: the benefits include
improved pilot comfort, productiv-
ity, and safety, and a lessened risk of
heat strain and fatigue; drawbacks
may include reduced payload.
Cockpit air conditioning
improves pilot comfort,
Productivity, and safety.
29
-------
INDEXES OF THERMAL STRESS
FOR HOT WEATHER AIRCRAFT OPERATION
The following tables were derived
from the U.S. Air Force's Fighter
Index of Thermal Stress.5171 * The
Fighter Index of Thermal Stress was
developed to indicate hot conditions
which can impair mental perfor-
mance of flight crews. Air Force
flight crews are assumed to be above
average in physical fitness. Age and
other differences from assumed
characteristics for Air Force flight
crews may require greater caution
for individual agricultural pilots.
These tables account for heat
exposure during flight and time on
the ground, using ground weather
measurements (shaded air tempera-
ture and relative humidity).
Assumptions include:
• Pilot is fully acclimatized to the
heat.
• Pilot begins work well-hydrated
and reasonably rested.
• Adequate fluid intake is main-
tained. (See Step 6, pages 22-25.)
• Pilot performs no mixing, loading,
or other moderate to heavy work.
• Pilot has no pesticide exposure.
• Summer flight clothing is worn.
These tables do not account for
protective garments.
Users should recognize the limi-
tations of these tables. The exposure
limits do not account for individual
variations in cockpit cooling capac-
ity or human heat susceptibility.
* Appendix IV contains a more detailed dis-
cussion of the Fighter Index.
ThaintoractkxidmiWheatslralnand tow-level exposuresto pesticides can be detrimental to pilot safety. People are often unaware of these minor effects, making this danger worse.
30
-------
Tables
INDEX OF THERMAL STRESS FOR HOT WEATHER AIRCRAFT OPERATION
(DIRECTSUN)
Air
Temperature
—Relative Humidity—
<10% 20% 30% 40% 50% 60% >70%
NORMAL.
Table 9
INDEX OF THERMAL STRESS FOR HOT WEATHER AIRCRAFT OPERATION
(MODERATE OVERCAST SKY)
Air
Temperature
—Relative Humidity—
<10% 20% 30% 40% 50% 60% >70%
Bi£:;";': fili ^y:K
" 70°F
85°F
NORMAL ."""" ".'•' --^•;--::":--; ;;;^ --?.--'-': ;-•
. . . -.•--- ' • " - '
:'**t •
CAUTION
JOO°F
105°F
110°F
115°F
'-''
• Normal /one covers conditions which
feelhot but are usually safe if reasonable
precautions are followed. Do not push
activities during the first hot days of
slimmer.
• Caution zone includes conditions
which are tolerable if adequate precau-
tions are taken. Effects on the body are
small, but subtle impairments of mental
performance can occur, including altered
learning curves, shortened time sense, im-
paired vigilance, and increased error rates
on tracking tasks. Even under ideal condi-
tions, internal body temperature remains
high for one hour after heat exposure,
although a pilot will feel comfortable in a
cc>oler environment within a few minutes.
• |Be aware of heat stress.
• ; Cool off between flights if cockpit is not
air conditioned.
• Limit exposure to heat on the gound to
ja total of 90 minutes, unless pilot has
had complete rehydration and recov-
ery from the heat.
• Danger zone covers conditions where
human defenses are inadequate. Heat
buildup in the body and dehydration
increase with the severity of conditions.
Associated effects include marked de-
creases in acceleration tolerance, marked
decreases in mental performance, such
as poor response to unexpected events,
and failure of the body's temperature reg-
ukting system, with increasing likelihood
of physical collapse.
• Postponement of work is recom-
mended if cockpit is not air condi-
tioned.
• Limit exposure to heat on the ground to
a total of 45 minutes, unless pilot has
liad complete rehydration and recov-
ery from the heat.
31
-------
Give First Aid
When Workers Become 111
SETTING UP A FIRST AID
PROGRAM
When workers become ill from the
heat> immediate response with the
right procedures can stop them from
getting worse. A good first aid pro-
gram prepares the way for people to
respond on the spot, without having
to guess what to do and scramble for
help.
Preparations for first aid should
include:
• Designating a person responsi-
ble on-site for resolving questions
about how to handle suspected cases
of heat stroke. This person should
have training and experience with
heat illness and be able to take charge,
make decisions, give directions to
others, stay with a sick worker until
the problem is resolved, and report on
the problem to medical personnel
and, at larger establishments, to
higher management.
» Establishing a line of authority.
At larger establishments, the person
responsible for dealing with heat
stress problems on-site should doc-
ument and report all incidents of
heat illness to the person who has
principal responsibility for managing
the heat stress program. This gives
an employer needed information for
handling heat stress situations.
» Training workers and super-
visors to treat heat illnesses, includ-
ing first aid procedures and proce-
dures for getting emergency medical
help.
• Maintaining first aid supplies
on-site. Supplies should include
water, a piece of material, such as a
bath towel for a large piece of card-
board, for fanning a heat stroke
victim, and a cotton sheet to soak in
water and wrap around a heat
stroke victim. These supplies should
be protected against contamination
from pesticides.
• Arranging for emergency care
with a nearby medical facility and
setting up emergency transportation.
The name, address, and telephone
number of the medical facility; travel
directions; and information about
emergency transportation should be
posted at the telephone at a central
location at the worksite. This infor-
mation should also be included in
worker and supervisor training.
Commercial pesticide applicators
should carry information about
emergency care and transportation
with them to each job site.
RECOGNITION OF
HEAT ILLNESS
Workers should not work alone in
the heat for long periods of time.
Workers who are trained and expe-
rienced should be able to recognize
early signs of overheating in them-
selves, but it should not be assumed
that they will always do so or will
always respond appropriately. Either
first line supervisors should watch
workers closely or a "buddy" rule
should be established for workers to
watch each other, so that a worker
who becomes ill will be noticed and
given first aid promptly. When one
worker becomes ill from the heat,
supervisors should take this as a
warning that other workers may also
be at immediate risk and may need
to cool down and drink more fluids.
GENERAL PRINCIPLES
Step-by-step measures for treating
heat illnesses are given in Table 1 on
page 4. The following measures
apply across the board:
• All persons should avoid direct
contact with clothing heavily con-
taminated with pesticides.
• Protective garments should be
loosened or removed only in an area
where there will be no exposure to
pesticides.
• A person who develops heat
illness should not do work which
requires chemical-resistant suits and
should avoid other work likely to
cause heat stress for the rest of the
day.
• A person who collapses or
faints for any reason should not be
allowed to work for the rest of the
day. Vital signs should be monitored
and medical personnel should exam-
ine the person before the person is
allowed to leave for home.
TREATING HEAT STROKE
Heat stroke is the most dangerous
illness that can result from the body's
overheating. When a person gets heat
stroke, the blood-clotting mechanism
and liver and kidney functions are
often severely damaged, the lungs
can accumulate fluid, the central
nervous system can be damaged irre-
versibly, and virtually all other organs
and tissues sustain injury. Heat
32
-------
A good first aid
program prepares
people to respond
to heat illness
without having to
guess what to do.
stroke can develop quickly without
symptoms of heat exhaustion.36
Heat stroke is always an immediate
life-threatening medical emergency.
When a worker gets heat stroke, body
temperature must be lowered as
rapidly as possible. This is at least
as, if not more, important than rush-
ing the worker to a doctor, although
the worker should be given medical
attention as quickly as possible.
Survival may depend on how quickly
cooling is begun. If necessary, delay
transporting the worker until cooling
procedures procedures have been
started.
To lower body temperature rapidly:
• Place the worker in the shade
if possible, remove the worker's
clothing and shoes, wrap the worker
in the sheet from the first aid supplies,
and pour water over the sheet.
• Cool the head with wet
compresses.
« Fan the worker with a towel or a
large piece of cardboard.
• Add water as needed to keep
the sheet wet, and continue the
cooling during transport to a medi-
cal facility.
When pesticide handlers and early
entry workers get heat stroke:
• Do not delay initial cooling in
order to do lengthy decontamina-
tion, but it is still important to avoid
exposure to contamination. Decon-
tamination by sponging with soap
and water will itself help cool the
body.
H Alert ambulance crews and per-
sonnel at the medical treatment
facility to the possibility of pesticide
contamination.
H Inform medical personnel of the
product names, EPA registration
numbers, and active ingredients of
all pesticides to which a worker was
exposed. If possible, bring the pesti-
cide labels along.
The on-site person responsible for
dealing with heat stress problems can
accompany the worker to the medical
facility to take care of these items.
FAINTING AND SALT
DEPLETION HEAT
EXHAUSTION
Fainting and salt depletion heat
exhaustion are two other forms of
heat illness which may occur.
• Faulting, or "heat syncope."
Fainting not associated with heat
exhaustion or heat stroke can occur
when unacclimatized workers stay
in one position too long without
moving around or do strenuous
work they are not used to doing, or
when there is a sudden rise in air
temperature or humidity. It is
caused by blood "pooling" in the
lower parts of the body and the
dilated blood vessels in the skin,
resulting in less blood going to the
brain.36
Treatment includes removal to a
cooler area and rest lying down.
Recovery should be prompt and
complete. If it is not, treat as a case
of heat stroke until proven other-
wise. Fainting can be prevented by
acclimatization and avoiding staying
too long in a stationary position.66
• Salt depletion heat exhaustion.
This illness is similar to heat exhaus-
tion arising from dehydration,
except that the victim usually does
not feel thirsty and usually has heat
cramps and vomiting. When pesti-
cide handlers and "early entry"
wprkers become ill with these
symptoms, pesticide poisoning must
also be considered. Diagnosis and
treatment of salt depletion heat
exhaustion should be done by medi-
cal personnel.
_
FOLLOWING UP ON INCIDENTS
When a worker develops heat
illness, the person who oversees the
employer's heat stress program
should evaluate how the incident was
handled and follow up with measures
necessary for improvement. A special
safety meeting should be conducted
with workers and supervisors to
review the incident, discuss how the
incident could have been prevented,
arid stress other key procedures for
preventing heat illness.
Employers should notify appro-
priate government agencies about
serious incidents, as required. By
law, OSHA must be notified if there
is a fatality or five or more workers
haive been hospitalized from one
accident.*
*29 Code of Federal Regulations 1904.8
33
-------
References
PRINCIPAL SOURCES
1. ASCC Working Party 61, Project Group 114, Aeromedical
Considerations of Thermal Stress and Survival. Prevention
of Heat Casualties, Draft Advisory Publication, Air Standard-
ization Coordinating Committee (Australia, Canada, New
Zealand, United Kingdom, United States), 1990.
2. Departments of the Army, the Navy, and the Air Force.
Prevention, Treatment, and Control of Heat Injury. Head-
quarters, Departments of the Army, Navy, and Air Force,
1980.
3. Field Manual: First Aid for Soldiers. Headquarters, Depart-
ment of the Army, 1988.
4. Leithead, C S., and A. R. Lind. Heat Stress and Heat Dis-
orders. Cassell, 1964.
5. NIOSH. Occupational Exposure to Hot Environments:
Revised Criteria 1986. U. S. Department of Health and
Human Services, 1986.
6. NIOSH. Working in Hot Environments: Revised 1986. U. S.
Department of Health and Human Services, 1986.
7. U. S. EPA. Goldman, R. F. Internal Report: Heat Stress Man-
agement Protocol. U. S. EPA, 1989.
8. United States Army Medical Research and Development
Command. Sustaining Health and Performance in the
Desert: A Pocket Guide to Environmental Medicine for
Operations in Southwest Asia. U. S. Army Research Insti-
tute of Environmental Medicine, 1990.
ADDITIONAL RESOURCES CITED
9. Allendorf, H. D. Letter to S. Shapiro. November 27,1989.
10. American Conference of Governmental Industrial Hygie-
nists. Documentation of the Threshold Limit Values and
Biological Exposure Indices, Fifth Edition. 1986.
11. American Conference of Governmental Industrial Hygie-
nists. 1990-1991 Threshold Limit Values for Chemical
Substances and Physical Agents and Biological Exposure
Indices. 1990.
12. Armstrong, L E, J. P. De Luca, and R. W. Hubbard. Time
Course of Recovery and Heat Acclimation Ability of Prior
Exertional Heatstroke Patients. Medicine and Science in
Sports and Exercise 22(l):36-48,1990.
13. Avellini, B. Av and N. A. Pimental. Effectiveness of a Porta-
ble Microclimate Cooling System in Reducing Heat Strain.
Abstract presented at the American Industrial Hygiene
Conference, Orlando, Florida, May 1990.
14. Banta, G. Personal Communication. April 8,1991.
34
15. Bar-Or, O. Temperature Regulation during Exercise in
Children and Adolescents. In: Gisolfi, C.V. and D. R. Lamb,
eds. Perspectives in Exercise Science and Sports Medicine,
Volume 2: Youth, Exercise, and Sport. Benchmark Press,
1989.
16. Bar-Or, O., R. Dotan, O. Inbar, A. Rotshtein, and H. Zonder.
Voluntary Hypohydration in 10- to 12-year-old Boys.
Journal of Applied Physiology 48(1):104-108,1980.
17. Bernard, T. E., and W. M. Hanna. Environmental Effects on
WBGT and HSI Using a Computer Simulation. Journal of
Industrial Ergonomics 3:103-113,1988.
18. Bellinger, R. R., and G.R. Carwell. Biomedical Cost of Low-
Level Flight in a Hot Environment. Aviation, Space, and
Environmental Medicine 46(10):1221-1226,1975.
19. Brouha, L. Physiology in Industry. Pergamon Press,. 1960.
20. Centers for Disease Control. Heat Stroke — United States,
1980. Morbidity and Mortality Weekly Report 30(23):277-
278,1981.
21. Davies, C. T. M. Thermal Responses to Exercise in Children.
Ergonomics 24(1):55-61,1981.
22. Dellinger, J. A. and H. L. Taylor. Measuring the Effects of
Neurotoxicants on flight Simulator Performance. Aviation,
Space, and Environmental Medicine 56:254-257,1985.
23. Department of the Army. Heat Injury Prevention and First
Aid. Headquarters, Department of the Army GTA 8-5-45,
1985.
24. Department of the Navy, Supply Systems Command. Effec-
tiveness of Three Portable Cooling Systems in Reducing
Heat Stress. Navy Clothing and Textile Research Facility,
1989.
25. Drinkwater, B. L., and S. M. Horvath. Heat Tolerance and
Aging. Medicine and Science in Sports ll(l):49-55,1979.
26. Ecobichon, D. J. Organophosphorus Ester Insecticides. In:
Ecobichon, D. J. and R. M. Joy. Pesticides and Neurological
Diseases. CRC Press, Inc., 1982.
27. Edwards, M. J. Clinical Disorders of Fetal Brain Develop-
ment: Defects due to Hyperthermia. In: Hetzel, B. S., and R.
M. Smith, eds. Fetal Brain Disorders — Recent Approaches
to the Problem of Mental Deficiency. Elsevier/North Hol-
land Medical Press, 1981.
28. Edwards, M. J. The Effects of Hyperthermia on Brain Devel-
opment. Birth Defects 18(3A):3-11,1982.
29. Electric Power Research Institute. Heat-Stress-Management
Program for Nuclear Power Plants. Electric Power Research
Institute, 1986.
30. Epstein, Y. Heat Intolerance: Predisposing Factor or Resid-
ual Injury? Medicine and Science in Sports and Exercise
22(l):29-35,1990.
-------
31. Fluid Replacement and Heat Stress. National Academy
Press, 1990.
32. Fuller, F. H., and P. E. Smith. Evaluation of Heat Stress in a
Hot Workshop by Physiological Measurements. American
Industrial Hygiene Association Journal 42(1):3237,1981.
33. Glenn, S., W. D. Eley, and P. A. Jensen. Evaluation of Three
Cooling Systems Used in Conjunction with the USCG
Chemical Response Suit. Hazardous Materials Control
3(5)54-59,1990.
34. Gribetz, B., E. D. Richter, M. Krasna, and M. Gordon. Heat
Stress Exposure of Aerial Spray Pilots. Aviation, Space, and
Environmental Medicine 51(1):56-60,1980.
35. Howell, P. Coroner Report 1412,1984.
36. Hubbard, R. W., and L. E. Armstrong. The Heat Illnesses:
Biochemical, Ultrastructural, and Fluid-Electrolyte Consid-
erations. In: Pandolf, K. B., M. N. Sawka, R. R. Gonzalez, eds.
Human Performance Physiology and Environmental
Medicine at Terrestrial Extremes. Benchmark Press, 1988.
37. Jensen, R. C. Workers' Compensation Claims Relating to
Heat and Cold Exposure. Professional Safety 28 (9):19-24,
1983.
38. Kilbourne, E. M. Background Information on Heat-related
Health Effects and Recommendations for the Prevention of
Heat-related Injury. Center for Environmental Health and
Injury Control, Centers for Disease Control, 1988.
39. Kilbourne, E. M. Diseases Associated with the Physical
Environment: Illness due to Thermal Extremes. In: Last, J.
M., ed. Maxcy-Rosenau - Public Health and Preventive
Medicine, 12th Edition. Appelton-Century-Cofts, 1986.
40. Knochel, J. P. Heat Stroke and Related Heat Stress Dis-
orders. Disease-A-Month 35(5):301-378,1989.
41. Lary, J. M. Hyperthermia and Teratogenicity. In: Anghileri,
L., and J. Robert, eds. Hyperthermia in Cancer Treatment.
CRC Press, 1984.
42. Lavenne, F., and J. Brouwers. Heat Acclimatization. In:
Parmeggiani, L, ed. Enclyclopaedia of Occupational Safety,
Third (Revised) Edition. International Labour Office, 1983.
43. Lee, C. H. Effects of Wick Contamination and Thermal
Component Variation on Thermal Indices. Unpublished
Ph.D. dissertation. Texas Tech University, 1986.
44. Levine, R. J. Personal Communication. January 8,1991.
45. Melnicoe, R. Letter to S. Segal. October 25,1988.
46. National Institute for Occupational Safety and Health,
Occupational Safety and Health Administration, U. S. Coast
Guard, U. S. Environmental Protection Agency. Occupa-
tional Safety and Health Guidance Manual for Hazardous
Waste Site Activities. U. S. Department of Health and
Human Services, 1985.
47. Nunneley, S. A. Aircrew Thermal Stress Index for Chemical
Warfare Operations: Concept and Development. NATO
AGARD, 1988. \
48. Nunneley, S. A. Heat Stress Effects of Aircrew Chemical
Defense Clothing. NATO Lecture Series, Course for Flight
Surgeons. U.S. Air Force School of Aerospace Medicine, 1983.
49. Nunneley, S. A., P. J. Dowd, L. G. Myhre, and R. F. Stribley.
Physiological and Psychological Effects of Heat Stress
Simulating Cockpit Conditions. Aviation, Space, and Envir-
onmental Medicine 49(6):763-767,1978.
50. Nunneley, S. A. and C. F. Flick. Heat Stress in the A-10
Cockpit: Flights Over Desert. Aviation, Space, and Envir-
onmental Medicine 52(9)513-516,1981.
51. Nunneley, S. A. and R. J. Maldonado. Head and/or Torso
Cooling during Simulated Cockpit Heat Stress. Aviation,
Space, and Environmental Medicine 54(6):496-499,1983.
52. Nunneley, S. A. and L. G. Myhre. Physiological Effects of
Solar Heat Load in a Fighter Cockpit. Aviation, Space, and
Environmental Medi.cine 47(9):969-973,1976.
53. Nunneley, S. A., and R. F. Stribley. Fighter Index of Thermal
Stress (FITS): Guidance for Hot-Weather Aircraft Opera-
tions. Aviation, Space, and Environmental Medicine,
50(6):639-642,1979.
54. Nunneley, S. A., and R. F. Stribley. Heat and Acute Dehy-
dration Effects on Acceleration Response in Man. Journal of
Applied Physiology 47(1):197-200,1979.
55. Occupational Safety and Health Administration. Field Sani-
tation; Final Rule. Federal Register 52(84):16050-16096,1987.
56. Pollack, S. H., and P. J. Landrigan. Child Labor in 1990:
Prevalence and Health Hazards. Annual Reviews in Public
Health 11:359-375,1990.
57. Quayle, R., and F. Doehring. Heat Stress: A Comparison of
Indices. Weatherwise, June 1981;120-124.
58. Ramsey, J. D. Abbreviated Guidelines for Heat Stress Expo-
sure. American Industrial Hygiene Association Journal
39(6):491-495,1978. .,
59. Ramsey, J. D. Practical Evaluation of Hot Working Areas.
Professional Safety, February 1987;42-48.
60. Richmond, D. M., and L. Mehler. Summary of Episodes
Assigned Priority Investigation Status in 1987. California
Department of Food, and Agriculture, 1989.
61. Richter, E. D., B. Cohen, M. Luria, J. Schoenberg, E. Weisen-
berg, and M. Gordon. Exposures of Aerial Spray Workers to
Parathion. Israeli Journal of Medical Science 16:96-100,1980.
62. Richter, E. D., M. Gordon, M. Halamish, and B. Gribetz.
Death and Injury in Aerial Spraying: Pre-crash, Crash, and
Post-crash Prevention Strategies. Aviation, Space, and
Environmental Medicine 52(l):53-56,1981.
35
-------
63. Richter, E. Dv B. Gribetz, M. Krasna, and M. Gordon. Heat
Stress in Aerial Spray Pilots. In: Tordoir, W. F. and E. A. H.
van Heemistra-Lequin, eds. Field Worker Exposure during
Pesticide Application. Studies in Environmental Science
7:129-136,1980.
64. Richter, E. Dv L. Kaspi, M. Gordon, S. Levy, R. Israeli, and N.
Gruener. Monitoring for Neurotoxic Effects from Low Level
Exposures to Organophosphate Pesticides. The Science of
the Total Environment 32:335-344,1984.
65. Robinson, M. D., and P. N. Seward. Heat Injury in Children.
Pediatric Emergency Care 3(2):114-117,1987.
66. Shibolet, S., M. C. Lancaster, and Y. Danon. Heat Stroke: A
Review. Aviation, Space, and Environmental Medicine
47(3):280-301,1976.
67. Shiota, K. Neural Tube Defects and Maternal Hyperthermia
in Early Pregnancy: Epidemiology in a Human Embryo
Population. American Journal of Medical Genetics 12:281-
288,1982.
68. Smith, P. W., W. B. Stavinoha, and L. C. Ryan. Cholineste-
rase Inhibition in Relation to Fitness to Fly. Aerospace Med-
icine 39:754-758,1968.
69. Sohar, E., J. Kaly, and R. Adar. The Prevention of Voluntary
Dehydration. UNESCO/India Symposium on Environmen-
tal Physiology and Psychology in Arid Conditions.
UNESCO, 1964.
70. Speckman, K. L., A. E. Allan, M. N. Sawka, A. J. Young, S. R.
Muza, and K. B. Pandolf. Perspectives in Microclimate Cool-
ing Involving Protective Clothing in Hot Environments.
International Journal of Industrial Ergonomics 3:121-147,
1988.
71. Stribley, R. F., and S. A. Nunneley. Fighter Index of Thermal
Stress: Development of Interim Guidance for Hot-weather
USAF Operations. USAF School of Aerospace Medicine,
SAM-TR-78-6,1978.
72. Stubbs, K. Coroner Report 1931,1983.
73. Turner, S. A. Personal Communication. July 26,1990.
74. Upfold, J. B., and M. S. R. Smith. Maternal Hyperthermia as
a Cause of "Idiopathic" Mental Retardation. Medical Hypo-
theses 27:89-92,1988.
75. White, M. K., and R. Ronk. Do You Have a Hot and/or
Strenuous Job? Professional Safety, May 1984;27-29.
76. Yarbrough, B. E., and R. W. Hubbard. Heat-Related
Illnesses. In: Management of Wilderness and Environmental
Emergencies. C. V. Mosby, 1989.
36
-------
APPENDIX I
Suppliers
EPA and OSHA have not evaluated the performance of these devices. These items are included for information purposes
only. EPA and OSHA have made every effort to include all known suppliers and regret if there are any not listed here.
SUPPLIERS OF COOLING GARMENTS
Including Suppliers of:
Combination Vest/Respirator Supplied Air Systems
Whole Body Cooling Systems — Air Cooled and Water Cooled
Cooling Vests — Ice Packs, Gel Packs, Air Pump Cooled, and Water Pump Cooled
Abanda, Inc.
401 Lee Street, N.E., S.uite 400
P.O. Box 2028
Decatur, AL 35602
(800) 522-2628
GEMPLER'S, Inc.
211 Blue Mounds Rd.
P.O. Box 270
Mt. Horeb, WI53572
(800)382-8473
Durafab
P.O. Box 658
Cleburne, TX 76031
(800) 433-1824
Encon Safety Products
1333 Northwest Freeway (77040)
P.O. Box 3826
Houston, TX 77253
(713) 460-5816
Fyrepel Products, Inc.
951 Buckeye Avenue - Box 518
Newark, OH 43055
(614) 344-0391
ILC Dover, Inc.
P.O. Box 266
Frederics, DE 19946
(302) 335-3911
Koslow Technologies Corp.
180 Osborne Street
Bridgeport, CT 06605
(800) 332-0306
Life Support Systems, Inc.
1400 North Shoreline Boulevard
Mountain View, CA 94043
(800) 878-5774 j
MSA ,
36 Great Valley Parkway
Malvern, PA 19355
(800) 657-2222
Racal Health and Safety, Inc.
7305 Executive Way
Frederick, MD 21701
(800)682-9500
Steele Incorporated
First and Washington
P.O. Box 7304 ,
Kingston, WA 98346 .!
(206) 297-4555
Trusafe
9369 8th Avenue South
Seattle, WA 98108
(206) 762-7407
Vortec Corporation
10125 Carver Road
Cincinnati, OH 45242-9976
(800) 441-7475
Wheeler Protective Apparel,
Inc.
4330 West Belmont Avenue
Chicago, IL 60641-4581
(800) 542-1152
SUPPLIERS OF SELECTED DEVICES FOR EVALUATING HEAT STRESS
AND HEAT STRESS CONDITIONS
Including Suppliers of:
Airflow Technical Products,
Inc.
P.O. Box M552
Landing, NJ 07850
(800)247-8887 RHS
Bacharach, Inc.
625 Alpha Drive
Pittsburgh, PA 15238
(412)963-2000 RHS
Brooklyn Thermometer
Company, Inc.
90 Verdi Street
Farmingdale, NY 11735
(516)694-7610 RHS
Personal Temperature Monitors (PTM)
Relative Humidity Sensors (RHS) and Indicator Cards (RHIC)
Wet Bulb Globe Temperature Monitors (WBGT)
Bruel & Kjaer
185 Forest Street
Marlborough, MA 01752
(508)481-7000 WBGT
Davis Instrument Manufacturing
Co., Inc.
Seton Business Center
4701 Mt. Hope Drive
Baltimore, MD 21215
(800) 368-2516 RHS
Howard Manufacturing &
Consulting, Inc.
3456 Altonah Road
Bethlehem, PA 18017
(215) 694-0939
Metrosonics, Inc.
P.O. Box 23075
Rochester, NY 14692-3075
(716)334-7300 PTM, WBGT
Omega Engineering, Inc.
One Omega Drive
P.O. Box 4047
Stamford, CT 06907
(800)826-6342 RHS
Quest Electronics j
510 South Worthington
Oconomowoc, WI 53066
.(414)567-9157 PTM
Reuter-Stokes
Vallen Safety Supply
390 Turner Industrial Way
Aston, PA 19014
(215)485-4715 RHS, WBGT
R.M. Young Company
2801 Aero-Park Drive
Traverse City, MI 49684
(616) 946-3980
Teletemp Corporation
P.O. Box 5160
Fullerton, CA 92635-0160
(800)321-5160 RHIC
Vista Scientific Corporation
85 Industrial Drive
Ivyland, PA 18974
(215)322-2255 RHS, WBGT
37
-------
APPENDIX
Sources for Obtaining Local Climate Profiles
NATIONAL WEATHER SERVICE
AGRICULTURAL WEATHER SERVICE CENTERS
Midwest Agricultural Weather
Service Center
Poultry Science Building
Room 220
Purdue University
Lafayette, IN 47907-5607
(317) 494-4317
Southwest Agricultural
Weather Service Center
"Texas A&M University
Soil & Crop Science Building,
Room 341
College Station, TX 77843
(409) 846-3216
Southeast Agricultural
Weather Service Center
P.O. Box 2246
Auburn, AL 36831-2246
(205) 844-4514
Mid-South Agricultural
Weather Service Center
P.O. Box 306
Stoneville, MS 38776
(601) 686-9311 Ext. 275
REGIONAL CLIMATE CENTERS
Western Regional Climate Center
5625 Fox Avenue
Reno, NV 89506-0220
(702) 677-3100
High Plains Climate Center
237 L.W. Chase Hall
University of Nebraska-Lincoln
Lincoln, NB 68583-0728
(402)472-6706
Midwestern Climate Center
Illinois State Water Survey
2204 Griffith Drive
Champaign, IL 61820
(217) 333-6780
Southeastern Regional Climate Center
1201 North Main Street
Capitol Center Suite 1100
Columbia, SC 29201
(803) 737-0800 or 0811
Northeast Regional Climate Center
1113 Bradfield Hall
Cornell University
Ithaca, NY 14853
(607) 255-1751
Southern Regional Climate Center
Louisiana State University
Baton Rouge, LA 70803
(504) 388-6870
-------
STATE CLIMATOLOGISTS
Dr. Richard McNider
Univ. of Alabama/Huntsville
Research Institute - Box 212
Huntsville, AL 35899
(205) 895-6257
Fax (205) 895-6677
Dr. James L. Wise
AEDIC/Univ of Alaska
707 A Street
Anchorage, AK 99501
(907) 257-2737
Fax (907) 276-6847
Dr. Anthony J. Brazel
Laboratory of Climatology
Arizona State University
Tempe,AZ 85287-1508
(602) 965-6265
Dr. John G. Hehr
Department of Geography
104 Carnall Hall
University of Arkansas
Fayettevffle, AR 72701
(501) 575-3159
Fax (501) 575-2642
Mr. William A. Mork
California Department of
Water Resources
Division of Flood
Management
P.O. Box 388
Sacramento, CA 95802
(916) 445-5800
Dr. Thomas McKee
Colorado Climate Center
Department of Atmospheric
Science
Fort Collins, CO 80523
(303) 491-8545
Dr. David R. Miller
Dept. of Natural Resources,
Mgmt. and Engineering
308 W. B. Young Building
1376 Storrs Road
University of Connecticut
Storrs, CT 06269-4087
(203) 486-2840
Dr. John R. Mather
State Climatologist for
Delaware
Department of Geography
University of Delaware
Newark, DE19716
(302) 451-2294
Dr. Thomas A. Gleeson
Department of Meteorology
Florida State University
Tallahassee, FL 32306
(904) 644-3417
Dr. Gayther L. Plummer
State Climatologist
Inst. of Natural Resources
Ecology Building
University of Georgia
Athens, GA 30602
(404) 542-1555
Mr. Manabu Tagomori
State Dept. of Land & Natural
Resources
Div. of Water & Land Dvlp.
P.O. Box 373
Honolulu, ffl 96809
(808) 548-7533
Fax (808) 548-6052
Dr. Myron Molnau
Agricultural Engr. Dept.
University of Idaho
Moscow, ID 83843
(208) 885-6182
Fax (208) 885-8923
Dr. Wayne M. Wendjand
Illinois State Water Survey
2204 Griffith Drive
Champaign, IL 61821
(217) 333-0729
Fax 217 333-6540
Mr. Ken Scheeringa
Agronomy Department
Purdue University
West Lafayette, IN 47907-1150
(317) 494-4772
Dr. Harry J. Hillaker, Jr.
State Climatologist
International Airport Terminal
Bldg., Room 212
Des Moines, IA 50321
(515) 281-4062 i
Stephen M. Welch (acting)
Computer System Office
211 Umberger Hall
Kansas State University
Manhattan, KS 66506-3402
(913) 532-6270
Fax (913) 532-6487
Mr. Glen Conner
Kentucky Climate Center
Department of Geography &
Geology
Western Kentucky University
Bowling Green, KY 42101
(502) 745-4555
Dr. Robert A. Muller
Department of Geography &
Anthropology '
Louisiana State University
Baton Rouge, LA 70803 ';
(504) 388-6870 i
Fax 504 388-2520 [
Dr. Bernard E. Dethier
1 Winslow Hall '
University of Maine |
Orono, Maine 04469-0163
(207) 581-7980 !
Mr. George J. Huffman
1123A, Jull Hall
University of Maryland
College Park, MD 20742
(301) 454-3110
Dr. David Taylor
State Climatologist
Massachusetts Department of
Water Resources :
469 Park Street j
North Reading, MA 01864
(617) 275-8860, Ext. 138
Fax (617) 271-0178
Dr. Fred V. Nurnberger
MDA/Climatology Program
417 Natural Science Building
Michigan State University
East Lansing, MI 48824
(517) 373-8338 or 355-0231
Fax 517 336-1076
Mr. Jim Zandlo, Jr.
State Climatology Office
University of Minnesota
S-325 Borlang Hall
St. Paul, MN 55108
(612)296-4214
Fax (612) 625-2208
Dr. Charles L. Wax
Drawer 5167
Mississippi State University
Mississippi State, MS 39762
(6010 325-3915
Professor Wayne L. Decker
Department of Atmospheric
Science
Univ. of Missouri/Columbia
701 Hitt Street
Columbia, MO 65211
(314) 882-6592
Fax (314) 882-5127
Professor Joseph M. Caprio
Plant & Soil Science Dept.
Montana State University
Bozeman, MT 59717
(406) 994-5067
Fax (406) 994-3933
Mr. Allen Dutcher
239 Chase Hall
High Plains Climate Center
University of Nebraska
Lincoln, NB 68583-0728
(402) 472-5206
Fax (402) 472-6338
Professor John W. James
Geography Department
College of Arts & Sciences
University of Nevada/Reno
Reno, NV 89557-0048
(702) 784-6995
39
-------
STATE CLIMATOLOG1STS (continued)
Prof. Robert LA. Adams
Dept. Geography/James Hall
University of New Hampshire
Durham, NH 03824
(603)862-3136
Fax (603) 862-2030
Dr. Mark D. Shulman
Dept. of Meteorology &
Physical Oceanography
Cook College, Rutgers Univ.
P.O. Box 231
New Brunswick, NJ 08903
(201) 932-9387 or 9024
Fax (201) 932-6769
New Mexico
No s.c. at this time
Mr. Keith L. Eggleston
1109 Bradford Hall
Cornell University
Ithaca, NY 14853
(607)255-1749
Fax (607) 255-2106
Dr. Jerry M.Davis
Department of Marine/Earth/
Atmospheric Science
Box 8208
NC State University
Raleigh, NC 27695-8208
(919) 515-7243/3056
Fax (919) 515-7802
Professor John W. Enz
Department of Soils Science
Fargo, ND 58105-5638
(701)237-8576
Fax (701) 237-7851
Dr. Jeffrey C. Rogers
Department of Geography
Ohio State University
103 Bricker Hall
Columbus, OH 43210-1361
(614) 422-2514
Dr. Ken Crawford
Oklahoma Climatologkal
Survey
University of Oklahoma
710 Asp, Suite 8
Norman, OK 73019
(405) 325-2541
Fax (405) 325-7689
(Inactive)
Atmospheric Science
Department
Oregon State University
Corvallis, OR 97331
(503) 737-3714
Pennsylvania
No s.c. at this time
Dr. Robert C. Wakefield
Department of Plant Sciences
Room 313, Woodward Hall
Kingston, RI02881
(401) 792-4549
Mr. Earl Rampey
South Carolina State
Climatology Office
1201 Main Street
Suite 1100, Capital Center
Columbia, SC 29201
(803) 737-0811/0800
Fax (803) 765-9080
Mr. Hal D. Werner (acting)
Agricultural Engineering
Department
South Dakota State University
Brookings, SD 57007
(605) 688-5673
Mr. Wayne Hamburger
Tennessee Valley Authority
Evans Building EB3W307A
Knoxville, TN 37909
(615) 532-4222
Professor John F. Griffiths
Meteorology Department
Texas A&M University
College Station, TX 77843-3146
(409) 845-7320/5044
Fax (409) 845-6331
Dr. Gail Bingham
Utah State Climatologist
Utah State University
Logan, UT 84332-4825
(801) 750-2190
Fax (801) 750-3376
Dr. Leonard P. Perry
Department of Plant & Soil
Science
Hills Building
University of Vermont
Burlington, VT 05405
(802) 656-0479
Fax (802) 656-0285
Dr. Patrick J. Michaels
Department of Environmental
Sciences
Clark Hall
University of Virginia
Charlottesville, VA 22903
(804) 924-0549/7761
Mr. Mark Albright (acting)
Atmospheric Sciences Dept.
University of Washington,
AK-40
Seattle, WA 98195
(205) 543-0448
Fax 205 543-0308
Dr. Stanley J. Tajchman
Division of Forestry
P.O. Box 6125
West Virginia University
Morgantown, WV 26506-6125
(304) 293-3411
Fax (304) 293-2441
Ms. Pam Naber
State Climatologist Office
University of Wisconsin
1225 West Dayton Street
Madison, WI53706
(608) 263-2374
Dr. Victor Hasfurther
Wyoming Water Resources
Center
University of Wyoming
P.O. Box 3067
University Station
Laramie, WY 82071
(307) 766-2143
Fax (307) 766-3718
40
-------
APPENDJX III
Methods for Deriving Tables 6 and 7
Method for Table 6
APPROACH FOR SETTING WORK/REST PERIODS
FOR WORKERS WEARING NORMAL WORK CLOTHING
Abbreviations. PSYCHROMETRIC CHART AND VAPOR PRESSURE NOMOGRAPH
Ta — air temper alw3 —
TmAjVi — nafnral wpf V>ll1h tPTYinpratllT'e
1. From psychrometric chart at right,
read Twb for Ta between 90° and 112°F
at relative humidities of 10%, 20%, 30%,
40%, 50%, and 60%.
natural ventilation with perceptible air
flow and Tg - 0. Calculate — WBGT with
no radiant heat for the temperatures and
relative humidities in #1.
3. (See Table A.)
A Calculate (Ta - WBGT) for air
PSYCHROME1
j^S\
£
ii
4O SO
A
\
08 .
^
^
•^i-
r —
f^5
X
-^^.
^IC CHART
^A;
/ $%
~y
'<
<^
<:
-^:
(/
"/
^- — '
-^
P
/
><
S
X
<^
^
X
^
^
^-*
90.
xC '
^
^
^
''
''*^
<-
•^-
95
/"/
^
^^^
\
^>
tx
~>,
rt>,
IOQ
V
4
V
/
~^
^
-^
_ — '
"*^v.
J^
I
/
/
/
/
7
1
y
/
<
^
^-
>-:
•\
-^
X
'^
-r-.
-v
^
/
/
•vy
/
^x1-
2
/
\
-,,-
~-
1~
/
/
\
f
^
xj
^
7
""-s
/
^
^
y
~.^
^><
"S-^
k^
/
^
v (
/'
\
j?1
"-
^
-^
/
\
/
/
\
^
^
><
*^
Mil
^
/
/
^
.!
/
^
^
N
\
•NLII
^*v
•\
'
^
\
:
-
:
^
/ 1
•
^:
j
I
•S:
12
9
6
3
0
temperatures (90°F to 112°F) at rela- Source: The Industrial Environment — Its Evaluation and Control, 3rd Edition. NIOSH Publication No. 74-117.
tive humidities between 10%
and 60%. (Second column, Table A)
B. Calculate mean (Ta - WBGT) under
each relative humidity. (Third
column/ Table A)
C. Designate a median reference rela-
tive humidity. (30% was chosen,
although any relative humidity in
this range will serve this purpose.)
Calculate differences between means
for relative humidities of 10%, 20%,
40%, 50%, and 60% and the mean for
30% relative humidity. (Fourth
column, Table A)
D. Round off values in 3.C. to assign
adjustment factors for each relative
humidity.
E. Assign air temperature adjustment
factors for radiated heat of the sun as
follows:
• No sun — no adjustment.
• Partly cloudy — add 7°F.
• Full sun — add 13°F.*
Table A
r
*! ^i
i
AIR TEMPERATURE ADJUSTMENT FACTORS
FOR RELATIVE HUMIDITIES AT AIR TEMPERATURES
BETWEEN 90° AND 1 1 2°F
Relative
Humidity Range Ta- WBGT
10% 22.26 to 29.47
20% 18.9 to 24.5
30% 16.1 to 20.3
40% , 13.09 to 15.19
50% 10.5 to 12.88
60% 8.05 to 9.87
Mean
25.87
21.7
17.5
14.14'r
11.5 ^
8.96, '
Difference
from 30%
8.37
4.2
3.36
6
8.54
Adjustment
Factor
-8° ^ \
-4°
+6° i
+9"°
* Adjustment factors for relative humidity derived from a concept in Jerry D. Ramsey, "Practi-
cal Evaluation of Hot Working Areas," Professional Safety, February 1987. References 17 and 43
were also consulted. Adjustment factors for radiated heat of the sun derived from a concept in
NIOSH/OSHA/USCG/EPA, Occupational Safety and Hwlth Guidance Manual for Hazardous Waste
Site Activities, Table 8-10,1985. Ramsey's approach foir estimating WBGT indoors is:
If, Air temperature warm—hot (Ta = 75-95°F)
Natural ventilation with perceptible air flow (Twb = Tnwb)
Minimal or no radiation (Tg = Ta)
Then, At a given relative humidity, Tnwb = Ta - (Ta - Twb)
And, .. . WBGT S Ta - 0.7 (Ta - Twb)
41
-------
4. Use ACGIH Threshold Limit
Values and NIOSH Recommended
Exposure Limits for heat stress
exposure for heat-acclimatized
workers4 (Table B)
5. Rearrange Recommended Expo-
sure Limits, showing adjusted air
temperature equivalent at 30% rela-
tive humidity and add intermediate
values. (Table C) Include qualifying
assumptions in a footnote to Table 6
in main text.
JACGIH (American Conference of Govern-
mental Industrial Hygienists), 1990-1991
Tlirtslwtd Umil Values, and NIOSH (National
Institute for Occupational Safety and Health),
Occupational Exposure to Hot Environments:
Revised Criteria 1986.
Table B
ACGIH AND NOISH
RECOMMENDED LIMITS
FOR HEAT STRESS EXPOSURE
FOR ACCLIMATIZED WORKERS
Light Work Minutes of Work/Hour
87°FWBQT 45
89°FWBGT 30
90°FWBGT 15
1Q2°FWBGT Ceiling Limit
Moderate Work Minutes of Work/Hour
82°FWBGT 45
85°FWBGT 30
88°FWBGT 15
98°FWBGT Ceiling Limit
Heavy Work Minutes of Work/Hour
78°FWBGT 45
82°FWBGT 30 j
86°FWBGT 15
95°FWBGT Ceiling Limit !
i
Table C
• ---...-• . .,
APPROACH FOR SETTING WORK/REST PERIODS
FOR WORKERS WEARING NORMAL WORK CLOTHING
Ta*
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
[108]
[109]
110
111
112
WBGT
74
75
75.7
76.6
77
78
79
80
80.5
81
81.5
82
83
84
84.6
85
85.5
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
Light
Norma
Norma
Norma
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
45/15
[40/20]
[35/25]
30/30
15/45
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Stop Work
Moderate
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Normal
45/15
[40/20]
[35/25]
30/30
[25/35]
[20/40]
15/45
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Caution
Stop Work
Minimum
Water
Heavy to Drink
Normal ... ,
Normal ' ' . _ • \
Normal
Normal :
Normal '•
45/ts '-.;•• ". V '•-•;
[40/20].-. ..-'.'
[35/25] '
30/30 1/2 pint
every
[25/35] 30 minutes
[20/40] Vapint •
every
1 5/45 1 5 minutes
Caution
Caution
Caution Vapint
Caution every
Caution 10 minutes ;
Caution
Caution
Caution
Caution
Slopwork
'- ' -
'30% relative humiditv
42
-------
Method for Table 7
APPROACH FOR SETTING WORK/REST PERIODS
FOR WORKERS WEARING CHEMICAL—RESISTANT SUITS
L. Work/rest periods are based on
Goldman's table for Level C protec-
•ion* — Tyvek coveralls with gloves,
soots, and respirator — and
idjusted + 5°F for heat-
icclimatization. (Table D)
>. (See Table E.)
A. Add 5°F to account for
radiated heat of the sun under
partly cloudy skies.
B. Add 13°F for full sun and
assign intermediate values for
work/rest periods.
Ralph F. Goldman, Internal Report: Heat Stress Mi
Table D
LEVEL C PROTECTION,* NO SUN,
ADJUSTED +5°F FOR HEAT ACCLIMATIZATION
Air i Moderate
Temperature Light Work i Work Heavy Work
75°F No restriction No restriction No restriction
80°F No restriction >No restriction No restriction
85°F No restriction ,No restriction 40/20
90°F 40/20 25/35 15/45
95°F 15/45 0 0
100°F "0 0 0
magement Protocol, Office of Research and Development, U.S. EPA, November 1989.
•)
Table E ]
APPROACH FOR SETTING WORK/REST PERIODS \
FOR WORKERS WEARING CHEMICAL-RESISTANT SUITS j
Air
Temperature
75°F
80°F
85°F
90°F
\
95°F
-Light Work-
Partly
Full Sun Cloudy No Sun
Normal Normal Normal
schedule schedule schedule
30/30 Normal Normal
[93°] schedule schedu e
15/45 40/20 Normal
[98°] [90°] schedule
Caution 15/45 40/20
[95°]
Stop Stop 15/45
work work
Work/Rest Periods
-Moderate Work-
Partly
Full Sun Cloudy No Sun
Normal Normal Normal
schedule schedule schedule
20/40 Normal Normal
[93°] schedule schedule
" 10/50 25/35 Normal
,[98°] [90°] schedule
Caution Caution 25/35
Stop Stop Stop
work work work
i
-Heavy Work-
i.
, Partly
Full Sun : Cloudy No Sun
35/25 ! Normal Normal
[88°] i schedule schedule
i
10/50 > 40/20 Normal
[93°] [85°] schedule
Caution i 15/45 40/20
,! [90°]
!
!
Stop | Caution 15/45
work
Stop Stop Stop
work , work work
6
Minimum
Water
to Drink
One half pint
every;30 minutes
One to 11/a pints
every 30 minutes
One pint or more
every 15 minutes
Same as above
Same as above 1
Adjusted air temperature values that account for radiated heat of the sun are given in brackets. '; (
43
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APPENDIX IV
Background on the Fighter Index
of Thermal Stress*
The Fighter Index of Thermal Stress
(FITS) is designed for easy use by
operational units to predict when
cockpit environmental conditions
during low-level missions may
jeopardize akcrew performance.
FITS must be recognized as a
specialized tool. Simplifying assump-
tions limit its use to most low-level
flight« 3000 feet) in fighter and
trainer aircraft, both single and dual
seat, with high-visibility bubble
canopies and aircrews wearing light-
weight flight suits. Data collected in
flight indicate that there is a relation-
ship between ground weather and
cockpit conditions at altitudes less
than 3000 feet above ground level.
The three zones indicated on the
FITS tables are interpretation guides.
They are not exact demarcation lines,
but represent the FITS values at
which most personnel will begin to
experience the heat-stress problems
as outlined. Before encountering
problems, an individual akcrew
member may withstand more or less
heat stress than is indicated. This is
because the terms "ground standby"
and "low-level flight" encompass a
range of activities, clothing require-
ments, and physiological conditions
that cannot be incorporated into a
simple index. As with any index, FITS
is like a map rather than an aerial
photograph, and its precision suits
the general environment in which it is
to be used.
Designation of Caution and
Danger Zones on the FITS table
seemed the most practical way to
alert users to the significance of high
readings. Since thermal physiology
involves relatively slow processes,
flight must be treated as but one
item in a sequence of events involv-
ing different environments and
metabolic rates. The specific limits
were set after thorough review of
the literature on the physiological
and performance effects of heat
stress, relating these to typical
conditions encountered by aircrews.
Although FITS estimates cockpit
conditions during low-level flight,
the numbers also indicate levels of
heat stress during the ground and
low-altitude portions of all flights.
This is the basis for recommending
cancellation of all nonessential
flights whenever the index exceeds
114.8°F WBGT. (WBGT is a special-
ized index of heat stress which
accounts for the effect of humidity
and air movement, air temperature,
and radiation. WBGT is not normally
reported by weather stations.) At
this level, even minimum preflight
and climbout times constitute a
significant drain on physiological
reserves which can compromise
performance in later phases of the
flight.
For light to moderate work, mul-
tiple studies show that a deep-body
(rectal) temperature of 100.4°F is the
upper limit desirable. Above this
temperature, mental performance
can be impaired, acceleration (G)
tolerance diminishes, and human
thermoregulation becomes ineffi-
cient. In fact, as deep-body tempera-
ture exceeds 100.4°F, an increasing
number of persons approach col-
lapse; and at 102.2°F, about 50% of
subjects are incapacitated.
USAF fighter crews are apt to be
more physically fit and better heat
acclimatized than most other sub-
jects used in reported studies, and
thus can be expected to perform
their work in hotter environments
without increased risk of physiolog-
ical compromise despite their
heavier clothing.
Potential users should clearly
recognize the limitations of FITS.
The nature of the data used and
simplifying assumptions restrict its
application to fighter/trainer aircraft
on missions involving significant
periods at or below 300 feet above
ground level. Exposure limits
provide only general guidance, out-
lining conditions where a significant
proportion of persons are expected
to encounter problems.
"Derived from Stribley, R. R, and S. A. Nunneley, 1978. Fighter Index of Thermal Stress: Devel-
opment of Interim Guidance for Hot-Weather USAF Operations. USAF School of Aerospace
Medicine, SAM-TR-78-6; and Nunneley, S. A., and R. F. Stribley, 1979. Fighter Index of Thermal
Stress (FITS): Guidance for Hot-Weather Aircraft Operations. Aviation, Space, and Environmental
Medkine, 50(6):639-64Z
U.S. GOVERNMENT PRINTING OFFICE: 1994— 515-003 /01037
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FAX 1-800-551-1128 !
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